Graphic card comparison

I’m going to buy a new graphics card but before I do I just want to check a few things. Hopefuly someone might have had a simliar upgrade as me and so will able to give me some info.
I’m running a PIII 933 with 512MB RAM and a Geforce2 MX400. Now Iwant to buy a Geforce4 Ti 4200. Will this upgrades improvement be limited by my CPU speed and RAM or will the change be quite noticable.
Any input would be appreciated.