Ditching unnecessary services and processes to free up ram made a considerable difference for me on 1G ram. I use FSautostart, which is at
http://www.majorgeeks.com/FSAutoStart_d5746.html . I have roughly 640M free on normal startup, but get 850 after running FSautostart. The game ran with 640 but with a bit of sluggishness at times, since running FS it's nice and smooth all the time. I just run FS each time after a reboot before starting the game.
You have to configure it on which services and processes to stop, and there's a bit of trial and error, but the interface is very good with advice on what can be shut down and what should not. Save your config as eg "SH3 autostart" with a shortcut on the desktop and it's a snap to run.
Edit: Note that AFAIK FSautostart is for XP only. MajorGeeks shows a 1.0 ver build 8, but Softpedia shows a 1.1 ver at
http://www.softpedia.com/get/Tweak/S...utoStart.shtml , ... they may be the same as believe my ver 1.1 came from MajorGeeks, but just in case.