I think it’s possible to send a newer laptop in to have it upgraded… you’ll have to chaeck manufacturer’s website.
There may also be external graphics cards… I can’t imagine that being good though.
Make sure you buy a graphics card that supports hardware overlay as that is the key to 3d performance according to industry professionals (…or so I hear).
You might also go through a VISTA optimization tutorial. There are a number of tweaks you can do and redundant processes that need to be turned off. I got a program in a 3d world (maybe it was ImagineFX) by a company called ASHAMPOO that automatically does many of these things for you… long after I had done them myself.
Other general tips… check your task manager and look at which processes are taking the most… if you’re not online, you may benefit from shutting down your anti-virus while modeling… if you’re running outlook you should certainly turn that off.
EDIT: FOR THE RECORD: Google “Tom’s Hardware Vista Tweak” and you should get all the help you need from that handy guide.