Modem doesnt want to work right with XP, and video looks like crap in games

I just upgraded to Windows XP, and I must say that so far I am not impressed. I had to make a dialer to get online through my IP (Prodigy). Everything worked fine for a couple of days, then no go. I spent an hour on the phone talking with Prodigy to no avail, and they left me with the number to Microsoft. I spent 2 hours on the phone with Microsoft tech support and he left me with running a system repair after not being able to get me online. Also, even after upgrading my video card to a new driver, and adding more ram to my system, my games look like dung. All grainy and no definition in the graphics whatsoever. The games seem to run slower and my control pad doesnt work very snappy anymore either. Any tips to these problems would be greatly appreciated. As of right now, I loaded Windows 98 back on along with XP. (dual booted)? I didnt partition the hd, it didnt make me, but I have both programs on my comp now. At startup it asks me which one that i want to boot to, 98 or XP.

About all that I can think of would be to check all the hardware that you have to see if it is winXP compatable and tyat you are useing winXP compatable drivers for all of it. I have had some systems not run the vid card right if the motherboard wasn't happy with the OS. It was a VIA so I installed the latest 4in1 and it worked.