Graphical glitches are normally graphic card related, so I would make sure drivers and Win 7 are all up to date, if that fails try swapping out a different card, maybe borrow a friends and test if that works ok.
I would say that card is almost bare minimum for F1 2010, and you will need to be running low graphical settings. Have you done the auto graphic setup in the game or manually setting the detail and res? What are your settings for these?
As its quite old now, maybe the card could just be deteriorating and it could just be time for a new one. I believe the effects of going too far with an overclock can be similar to when a card degrades and overheats naturally.