Hi, I am having an annoyance at the floating items glitch
This has nothing to do with the video card, absolutely nothing!, this is to do with havok and the way it's been implemented in this game, one I see in all play throughs is a giants club floating upto the heavens, also any objects like rocks floating are because of bad placement during development.
But that aside, you do need to upgrade that card, personally I would not settle for anything less than Nvidia GTX260 minimum, ATI Radeon HD5850 or HD5870.