If you're having problems with Windows XP stability, you either have a hardware problem, a massive amount of spywareor a virus, or you're not doing something right. Or you're running an ancient piece of software known to be incompatible with XP (i.e., Easy CD Creator 4.x or earlier).
If you're having a problem with Windows 98 or Me, you should upgrade to Windows XP. By upgrade, I mean format your system and install from scratch, not run the "upgrade" option.
If you run Linspire, you'll probably have more compatibility issues with Windows apps. It's a version of Linux designed to have some Windows compatibility, but just how much is debatable. There really aren't any huge issues with the operability of Windows XP as long as you stay up to date on your Windows updates, keep the firewall enabled, and run a good virus scanner like you ought to (plus being intelligent enough to avoid adware/spyware helps).
Intel Q9450 @3.2GHz, Gigabyte GA EP45-UD3P, 4 x 2GB G.Skill @4-4-4-12
Antec P160SW case (modded), Xigmatek 750w PSU
3x 500GB (RAID-5), , OptiArc 7200S, ASUS E818A3T
Creative X-Fi XtremeGamer, Hauppauge HVR-1800, Radeon 4890