[geRV]

Last vid card i bought was almost a year ago, the radeon 8500 and its still going strong. You buy video cards as you need them, if games run well on settings you use on your current card theres no real need to upgrade as fast as possible.

Theres a load of overclocking programs for gfx cards, powerstrip is one of them.

Theres some difference between 64,b and 128mb cards. The memory on your graphcs cards is all for texture handling. any given texture in a game has a fileseize and the size of this file is the amount of memory it take sfrom the graphics card to process it, for example a 1meg tecture in a game will take up 1 meg of memory on your graphics card. 64mb of ram is really the minimum these days, 128mb of ram allows for higher res textures since the card has more memory to process them.

Games like doom 3 will require 80mb of textures in any given scene on high detail so if you have a 64mb graphics card then its not gonna look as good and will most likely chug your system with hard disk accesing to use space for the textures. The "nv-30" is supposed to be out before christmas, if thats the case then the ti-4600 cards will drop in price and you can pick up one for cheap.

As for 16\32 bit there is a difference 32 bit colours are better defined than 16 bit, play something like moh:aa in 16 bit then switch to 32 and you will see the difference.