Radeon 9550 without driect 3d acceleration?

Hello everyone,
Let's start at the beginning 2 weeks ago I had a problem with my system: it didn't send signal to my display, so I went back to the shop where I bought it. There they figured out that my mobo wasn't working properly. The guys there wanted to change it (because it was still in warranty) to an asrock but it kept blocking. After they tried with another videocard (9600xt->9550) it worked nicely. When I tried to install Win XP suddenly a blue screen appeared with some writings on it: dumping physical memory, etc. They gave me another memory but another make than the other one. Here comes my question.
My sistem seems to be slower from now on, than it was before with the older parts. I found out an interesting thing: when I run dxdiag I don't have direct 3d menu and acceleration(not available). Maybe this is why the movies and scrolling down in total commander and mozilla is so slow. How can this be? I installed the latest driver from amd's site. Please help me with this
Thanks Peet

I'm usnig asus a7v600-x mobo and 512 mb pqi and 512 mb aeneon memory. DDR1