yeah, HP is a very good quality systems, (even though I build my own).
I helped a friend this summer to buy a system, and got her a HPa250n Desktop w/ a 17" Viewsonic DVI Flatscreen. It originally came with a GeForce4MX AGP Video Card, but it didn't include a DVI port, so she got the ATI Radeon 9800 AGP Video Card. It upgraded fine, and the build quality is excellent!
In Summery: If i don't build my systems, I'd get an HP system, they are awesome!