Blender even laggier with Windows Xp than Vista !??!!?

Ok here’s my problem. I had a Dell Inspiron 1501 laptop with windows which on which I would run Blender 2.45. I had :

1gb of Ram (mobile AMD Sempron)
3500+ processor 789Mhz
and 60Gb hard drive

At first everything was ok, but as I got more experienced and started dealing with higher-poly models, its started getting a bit laggy. So i decided to order 2gb of ram and put Windows Xp SP2 on my laptop instead. Now i have 2.37 gb of ram, but everything else is the same. But now, when i run Blender, the simple act of subdividing the initial cube once makes the screen lag when i try to rotate the screen.

What should I do now…?

I dont know mgch about these problems but it might be an outdated grafix driver problem u got the latest drivers?