the recommended ram now is 2GB.
1GB will get you no-where
reformatting will only give you like 100mb of ram depending on how much shit you have installed,
most you can do is close down everything you have running,
and then attempt playing,
another option =
Start > Run > Msconfig
go to Startup and disable pretty much everything except Display Drivers and Mouse/Keyboard Shit.
then go to Services > Tick the Hide all Microsoft Services and untick all the thing you dont use,
but if you do it wrong and shit you can fuck up most programs,
so just be a smart one and go buy another 1GB stick.