hi, I'm having a lot of trouble trying to play the sims 2 and I'm getting really frustrated

And now as I look through all these sims forums trying to get it working , hearing all the cool things you can do , it makes me want to play even more!! so I hope someone can help me
Okay , heres the story. We bought the Sims 2 about 2 or 3 months ago, and we couldn't get it to work on our old computer, The computer was crap , it crashed all the time so we just accepted the fact that we'd have to wait until we got a new computer. We took the game back.
Now, 2 weeks ago we bought this brand new computer, and then for christmas got the sims 2 again. We've installed it, and today I reinstalled it again, and still it doesn't work
It goes through the little video thing at the start and then to the part where it says Sims 2 - chlorinating car pools, (etc, thats the only one I can remember) Then when it gets to what I assume is the last one, it stays on that for a second then , it either just restarts with no warning, or it goes to a weird messed up version of the desktop and gives 2 error messages , being something about the ialmrnt5 display driver, then saying it would have to restart, and it does.
If I need to give the exact message I can try the game again , and write it down.
I am running Windows XP professional, and have about 52 gigs free (now that the game is installed)
Please help!