At the end of the day, unless you are doing graphically demanding applications, you should not see any difference.
That being said, I have no proof to back it up, but - I think it really depends on the motherboard and chipset or integrated graphics used.
I have noticed on several machines that had integrated graphics (in particular Intel integrated) by upgrading to the cheapest graphics card that cost ~£20, I noticed a small increase in performance of general computing - starting up and launching other application.
I personally attributed this to offloading the graphics processing from the chipset - again, this is just personal experience, I have no proof or benchmarking to back it up.
How much memory does your system have? Which OS are you using? – Isxek – 2010-04-07T15:04:45.143
Win 7 Ultimate. 4 gigs of ram. Core Duo 2 @ 1.86mhz – Eduardo Molteni – 2010-04-07T21:25:27.930