I never tried to install #2, so I couldn't tell. But I give you better chances.
I must say that I was very impressed with Backtrack 3beta. It has some loose ends, of which the installer is one.. and a couple of menu items that didn't work properly. But on the other hand, it's very *bling* pretty
But it depends, if you want your penetration testing and network mapping tools installed on your system, you'll want Backtrack and I think you'll be better of with BT2 until #3 gets it's final release.
If on the other hand you want a Slack based desktop, Vector is a very good option. You can also add the tools included in Backtrack to your Slack/Vector install, although the easiest and most generally useful IMHO (AutoScan-network) will get you in terrible dependency troubles. It needs Gnome libraries
I mention this because I take it you are new to the world of Linux? Backtrack is a specialized tool rather than a complete desktop system. Although anything can be made into anything of course. Just don't expect it to be -like- easy
