Hmmm...
When you say it won't install, do you get an error message of any sort?
I haven't seen what came with the kit yet. I'm curious if there's a number to call for support?
Also, is it a DVD. I'm at home now, not at work so I don't remember if there is a separate DVD for the 2008 64bit version. I just installed 2009 and remember that there were separate disks for 32 and 64bit versions.
Also, check the approved graphics cards here:
www.solidworks.com/sw/videocardtesting.htm
An unapproved video card shouldn't keep it from installing though.