Transfer speed is significantly lower for externals (60 MB/s for USB 2.0 vs 300 MB/s for a SATA drive). Not much of an issue for just occasionally mirroring files, but can become a bit of a bother for common use. Personally I use an internal drive to store everything that isn't an installed program, then mirror that internal drive to an external drive every couple of months for backup purposes.
But back on topic, my plans for Dragon Age are to wait for the GOTY edition that will probably contain all the inevitable DLC. Although my plans may easily end up changing once it's released and I'm able to read what people have to say about it (of course changes in plans could go in either direction, from "buy it now" to "I'll pass").

yay for not having CPU to run the game.
i am on single core 3200 and cannot even run Assasin's creed altough i gotz 4850...
but if upgrade cpu i gotta got new mobo and new psu and new ram
so yay
ain't happening anytime soon

Most externals are simply a PATA/SATA drive in an enclosure, even if the enclosure sometimes contain more advanced functions than just a controller (such as a NAS with its SMB sharing, and optional FTP/web/bittorrent/other), though I have seen a drive with a mini-USB port directly on the drive.

My rig can run this, no problemo.
I haven't played a game that required me inserting a disc (bypassing them with cracks don't count) in a long time. I love digital distribution. And that's where I'm getting my copy. But it's nice EA/BioWare are actually realizing that we don't like this evil stuff called DRM.

Oh, I've got an enclosure and several different drives for it. And the internal drive is 320 GB. I just need to free up some space.
(Most of my drive is filled with Doctor Who episodes. I'm watching all of the surviving episodes in order.)

This has just gone gold (off to print) and all 3 versions will be out Nov 3. There doesn't appear to be a delay on the ps3 version anymore.
I think the developers have said it fits on one DVD 9, if so It'll take some installation to get it up to the initial 16 GIg (as reported by a developer) for a plain old english install (more space for multi language files).

Hey, look! There's an opening post in this thread! Didn't see it before :-P
Damn, I'll need to get some space free on the games partition... or I could install on C. On the other hand, I probably need to upgrade anyway, my Athlon 64 X2 3800+ at 2 GHz may not be able to run it comfortably, seeing how it's below the minimum specs. And the GeForce 7950 might be pushing it as well.
Oh well, I'll get the CE at launch and have it wait for an upgrade.

During the last couple of weeks speculation has been bandied about how many discs would be needed to ship that (projected 20 gigs) to users and how big the digital download install would be. Derek French (Bioware) did a 'properties' on his install and listed it in bytes, coming to roughly 16 gigs. He said the game is to be manufactured on standard dvd 9's and will support many languages. The basic single or 2 language version releases should fit on one dvd 9 but the true multilingual releases will require 2 discs. They are using basic rar compression though, nothing fancy.
The 20 gigs is just a basic usage number to allow for installation, swap files and save games.
I'm not looking forward to downloading this from gamersgate.uk but Its locked in now so here's to days of downloading from them... I'm fully expecting their download service to be even crummier than usual just because of Dragon Age.

20 Gb of my precious hard drive? =(

Oh come on now, Hard disks prices have been falling for some time now =)

I know that. But not only is it often far cheaper to buy OEM internal + enclosure, but often the drives sold as externals are 'refurbished' internal drives. Not good.

As above: often more expensive + refurbished drives = worse deal.

We've got no end of Dr Who episodes recorded to DVD here. I think a drive or two would have been cheaper. :D