I've installed Baldur's Gate from GOG, then a full install of GG2 and the ToB exspansion. I downloaded the BGT mod and ran the installation without any problems.

Doesn't work though. When run BG2 I don't get the option for a new game of BG.

I've never played around with mods on this game before so I could be doing something wrong.

Anyone know what I may be doing wrong?

Did you follow the readme to the letter? If so, selecting multiplayer and pressing new game should put a newly created character into candlekeep. Carefully reading readme and reinstall would probably be the best bet

I did follow it to the letter...I didn't see where it said to select multiplayer. It just says to click on BG2 and select new game.

Also, my understanding was that I wouldn't need the disk but it won't launch with the ToB disk in the drive.

Oh, right, singleplayer, sorry. Well you are supposed to remove all the game discs from the drive during the installation, since it will bork it. Yes, I don't really know what an issue could be since I have never, ever heard about the bug. Did you just try complete reinstall of the both games + the MOD? uuu, I just remembered, did you really have at least 25 GB of free space while installing it? I'm not sure if it even says something when you don't

Here's what I did:

1. Installed Baldur's Gate via Gog.com download.
2. Installed Baldur's Gate 2:SoA via CD, full install option (4 disks). -Removed disks from drive.
3. Installed Baldur's Gate 2: ToB Expansion via CD, full install option (1 disk). -Removed disk from drive.
4. Extracted BGT .rar mod to the BG2 directory.
5. Ran BGT install, entered path to BG1 install directory.
6. Waited 20 minutes while it did it's thing.
7. Install finished with no errors reported.
8. Double-clicked on the BG2: ToB executable and it asked for the disk.
9. Inserted disk and it loads the standard bg2:ToB.

Edit: Forgot to mention that I installed the latest patch from Bioware's website for ToB...the version number of the patch matched what the BGT readme specified...

...and I have around 70 gigs free on the drive that everything is installed on.

It seems to me you've installed everyting right, but you should doubleclick bgmain.exe inside the folder you installed the game into, NOT BG2TOB.exe. The latter starts up the default game (the one your registry points to), while bgmain is uded to start the modded game of the folder it's in.

Thanks Dub! That seems to have been the issue.

When I run that executable, it starts up and looks just like BG2, but when I start a new game it runs the cinematic for BG1 and I start in Candlekeep. I'm assuming that's how it's supposed to work.

If I want to install some mods for BG1, should I have done that before running the BGT install?

BG1 mods aren't made for BGT, look for BGT specific MODs. And, of course, you install those after BGT.