In case you didn't know, Eidos seem to have misinterpereted the petition for a source release and instead given us all three Thief games in a single pack under The Thief Collection.
This Christmas morning I felt the familliar shape of a DVD box wrapped up. I opened it to find The Thief Collection.
Judging by a few guys' attitudes towards it in the IRC Channel, the general consensus seems to be: "Want it, not sure if it will work".
So as my Christmas gift to these people; I shall testify to the Thief Collection:
It works.
DDFix is still required for the first two games, however. But due to the fact that they are pre-patched to the latest versions, a lot of the complications that arise in applying DDFix are eliminated. I run Windows 7 Ultimate 64-bit on a Dual Core processor and DDFix was all I needed to get Thief Gold running. I did, however have to manually apply it with a hex editor which was no trouble (you search for DDRAW.DLL and change the very first instance of it to DDFIX.DLL).
However I must stress that you must launch the game first and let it crash. This is important. A file called cam.cfg is not applied until you hear the words "Welcome, young Garrett" and if you apply DDFix before this then you will have to reinstall the game.
So the steps (for Thief Gold but should work for #2 as well):
1. Install the game
2. Download DDFix and copy the files to the same folder as THIEF.EXE http://timeslip.chorrol.com/ddfix.html
3. Launch THIEF.EXE and enter the training. If you are on a Dual Core processor, let the game crash, ctrl+alt+del and end THIEF.EXE
4. Apply DDFix in whatever manner is appropriate to you, either with the GUI or a Hex Editor. The latter may be more reliable.
5. Open cam.cfg in Notepad and change the line: "game_screen_size" to your resolution in this format "width height" --- If this line does not exist, do not add it. Launch the game first and let it crash.
6. Open DDFix.ini in Notepad and change the top few lines to match this resolution. It is CRUCIAL that they match.
7. Launch Thief as normal and enjoy.
In the next episode: Applying the famous orgy's and daemonite's texture patches (I haven't done this yet, not sure if it will work).
Merry Christmas to you all!

Notes on Thief 2:
Thief 2 follows very much the same procedure as Thief, however it won't crash in the same way that original Thief does. I found it only crashed if I tried to kill Basso in the first mission, and then cam.cfg wouldn't generate.
Instead, for Thief 2 you must enter the game, let Basso tell you about the lock on the side door and then exit the game normally. cam.cfg will then be populated, change the resolution line, patch Thief2.exe for DDFix and then play the game.
Further notes:
DDFix has one tiny side effect, the main menu, loading screens and pause menu will be in a lower resoluton. I'm not sure what causes this. The text will be a little fuzzy. It's still legible, but it is ugly. You will not have such problems in-game however; it still looks perfect.

Awesome stuff! I feel like hunting for the collection in my local retail store.

That crash is the Dual Core crash, it's also the crash that you need to occur before you install DDFix.

is it this one
http://www.amazon.co.uk/Thief-Collection-Dvd-Video-Game/dp/B00172HK58/ref=sr_1_2?ie=UTF8&s=videogames&qid=1261745392&sr=1-2
or this one
http://www.amazon.co.uk/Thief-Complete-Collection-PC-DVD/dp/B002LVUKIS/ref=sr_1_1?ie=UTF8&s=videogames&qid=1261745392&sr=1-1
? Or it doesn't matter?

http://www.amazon.co.uk/Thief-Complete-Collection-PC-DVD/dp/B002LVUKIS/ref=sr_1_1?ie=UTF8&s=videogames&qid=1261745392&sr=1-1
This is the version that I have, the first link doesn't look real to me.
Also, the next part of the guide:
Daemonite Orgy:
Two lovely people from the Thief community made some wonderful patches for Thief 1/Gold that update the textures to Thief 2 quality. Orgy updates the textures while Daemonite's adds noses and thumbs etc to the character models.
1. Download Darkloader http://www.thief-thecircle.com/download.asp?fid=272
2. Install and add the relevent paths for your Thief games
2a. Under Windows 7, it was necessary for me to run Darkloader under Windows XP compatibility settings or it crashed while we optimised Thief, leaving the game unplayable!
3. Choose to optimise Thief
3a. I found that my install.cfg was actually configured wrong. Here is how mine looks now:
install_path C:\Program Files (x86)\Eidos\Thief Gold
language english
resname_base C:\Program Files (x86)\Eidos\Thief Gold\RES
load_path C:\Program Files (x86)\Eidos\Thief Gold+C:\Program Files (x86)\Eidos\Thief Gold
script_module_path C:\Program Files (x86)\Eidos\Thief Gold+C:\Program Files (x86)\Eidos\Thief Gold
movie_path C:\Program Files (x86)\Eidos\Thief Gold\movies
Check your install.cfg and make sure it looks something like this. For me, Darkloader added duplicate paths in some areas and this caused Thief to crash on startup.
4. Create a folder in your Thief directory called "fam"
5. Download http://thief-thecircle.com/download.asp?fid=597 and extract it to the newly made fam folder
6. Download Daemonite's http://thief-thecircle.com/download.asp?fid=590 and extract it to your Thief folder (this does not go in "fam")
7. Open up DARK.CFG and add the following line (anywhere)
ObjTextures16
8. Ensure that your video settings in Thief are set to "High Character Detail" and that "Hardware" is ON.
Your Thief Gold install will now look beautiful!
I should mention that this entire guide applies to both Thief: The Dark Project and Thief: Gold

Funny fact: I have single core processor

*Vote for Sticky*

Is it a Hyperthreading processor?
+1 ;)

Yep, it is.

The same crash will occur, in that case. I probably should have mentioned that it crashes on both HT and Dual Core.
In other news:
The next update will be a report on if the game runs under Wine in Linux.

Attempts to run Thief under Linux have so far been unsuccessful.
Also, on another note: Thief Gold and Thief 3 don't require the DVD to be in the drive, but Thief 2 does.

I ran Thief 2 under Ubuntu a couple years back with a demo version of an emulator just to see if it could work. I think it was called Cedega or something. It was a little slow, and I wasn't able to edit any visual or CPU settings for the emulator, but it was actually playable.

Cedega is just a version of Wine that you have to pay for that includes a launcher.