I realize that this is an odd place for a question about a completely different retail game site, but Direct2Drive doesn't have a forum of its own, and I know several people here use it.
About a week ago, I bought a copy of Tom Clancy's Splinter Cell off of Direct2Drive. However, I haven't been able to install it, because some kind of error message pops up every time I try to run the installation executable program. I gather that there's some kind of compatibility issue with Windows Vista Service Pack 2. I've sent their support crew a ticket, but they haven't responded yet. I'm starting to wonder if they ever will.
I guess I'd like some advice on what to do now. Is Direct2Drive's support team any good? If not, what are my odds of getting a refund?

I don't know how good they are cause i never had to call them up, but I remeber at least one fairly recent situation where someone seems to have got a refund from D2D...
My advice would be, if you can't troubleshoot the issue, wait for their reply and if / when it becomes apparent that they can't solve the problem somehow, ask for a refund...

Whats the error message say?

Error Code: -5006 : 0x80070002
Error Information:
>SetupDLL\SetupDLL.cpp (1281)
PAPP:Tom Clancy's Splinter Cell
PVENDOR:Ubi Soft Entertainment (http://www.ubi.com)
PGUID:A174402A-2EE6-4B86-A930-7BC85A9933BD
$7.1.100.1248
@Windows Service Pack 2 (6002) BT_OTHER 24176.59

Have you tried disabling your AV during isntall ? Is it Mcaffee by any chance ?

Yes, I am using McAfee, and disable it how?

You just right click the McAfee icon and disable it if I remember correctly. As for your game did you start installing it and then it got interupted or crashed or something like that?

I can't seem to disable it... maybe it's because I'm on a college campus network right now, but whenever I dry to disable the On-Access Scanner, nothing happens. If I try to End the Process with the windows task manager, I get an "Access Denied" message.
What happens when I try to install the game? Well, I open up the installation program by double-clicking the Setup executable. Then it prompts me to enter a language. Once I've selected one, the installation starts, and about a second later I get the error message posted above, along with the text:
"An error (-5006 : 0x80070002) has occurred while running the setup. Please make sure you have finished any previous setup and closed other applications. If the error still occurs, please contact your vendor: Ubi Soft Entertainment (http://www.ubi.com)."