which OS to use?

I currently am using XP Home edition, and I’ve been having all kinds of performance problems. I went through all the normal troubleshooting steps with the assistance of people on this forum and I’m still back where I started. One of the suggestions was for me to use XP Pro edition. I just want to make sure that XP Pro is the best version of Windows for me to use before I pluck down my $199. Is the NT 2003 version better? I want an OS that does a good job of managing memory, and is better performing.

Thanks for your ideas
Rick