Sometimes if your sim is in a bad mood they won't want to change their appearance or if there is an event going on.
As for you Video Card check Best Buy, a good one can be a decent chunk of cash so until you save up turn your settings way down. Also you may want to check on your ram. I was just reading another thread in this board and seems like allot of people that are having problems don't have enough.
I know I have 2gb ram, Nvidia geforce 7600 video card, and a 3.06 ghz processesor and I don't have any issues at all.
Here's a link to the BB site:
http://www.bestbuy.com/site/olspage.jsp?id=pcmcat168200050003&type=category&cpncode=733a2944-d0c0-441e-85c8-e593bd77a94eRemember that you can only have as good a video card as you have slots on your motherboard so you may just want to pack the tower up there with you if you go and dump it on the geek squad(or whatever they have) desk and say"Tell me what I can get."
*Fixed the link*