you will be fine for a good while yet with the 9700 card.
reduce the amount of unneeded services and background programs running and turn off all of the graphical niceties in xp to free lots of ram that you can put to good use in games in the meantime. i saved around 60-70mb at start up just by doing this alone.
check out click here the 'safe' settings should be fine for most set ups 'gaming' also gives me no problems.
use start/run and type 'msconfig' and untick everything listed except av and firewall under the 'start up' tab to stop programs starting with windows automatically.they will still start when you want them by selecting the shortcuts etc.
set control panel/system/advanced/performance/settings/visual effects to 'adjust for best performance'
I'm going to add some more anyway as its a cheap upgrade.