first off your card is only the bog standard one sorry to say it that way but you seriously need to think of upgrading it especially playing games like GTA3 and 4 you should go for the TI sderies you can pick a good TI4200 and 4400 for around the £65 to £75.
have you made sure you have the latest patches for your games also it may be a good idea to get a bit more memory maybe get another 128 megs it is very cheap sdram now you could pick a stick up for no more than £10 on
www.ebay.co.uk.
if you can play games ok and some won't then it is probably patches you need for the games that boot you back to desktop.
i have 512 ddr ram xp pro a TI4400 graphic acrd and playing Max Payne is no good it boots me to the desktop untill i downloaded the patch now it works great, so keep that ijn mind.
so check for patches get a bit more memory and try when you can to get a better graphic card, it has got nothing to do with your motherbaord mate.