format and re-install

I am going to format and re-install my system and would like input on the best way to install fs9. I have an 80GB WD Cavair (current OS drive and FS Drive) and a 250GB WD Cavair (has data and extra storage). I am re-installing with XP ultimate and would like to know if it would be good to keep the OS on the 80 GB drive with FS9 or keep the 80GB for just the OS and maybe PS7 and other apps and use the 250GB for FS9 and add-ons? Thanks on advance.