Lesser of 2 evils

I am looking for opinions as to which vid card I should use based on what I have ATM.
PNY Nvidia G-Force FX 5200 with 128M
or
the on-board ATI Raideon Xpress 200 with 256M
Now, if the PNY would be the better of the 2 my next question is...by adding it to the PC, does the BIOS disable the on board video or do I have to do that manually?
thx
MC
PNY Nvidia G-Force FX 5200 with 128M
or
the on-board ATI Raideon Xpress 200 with 256M
Now, if the PNY would be the better of the 2 my next question is...by adding it to the PC, does the BIOS disable the on board video or do I have to do that manually?
thx
MC