Windows XP performance

Fragmentation, bloatware, malware, viruses, adware, spyware, lack of free space, too many startup programs, clogged /fragmented registry, not to mention hardware problems.

You didn't mention what [i]"one of the commercial utilities"[/u] was, which would have helped. Let's run through the above possibles.

Fragmentation should be your first route ALTHOUGH how much free space you have left actually matters very much. Given that any defragmentation tries to join up broken files - there HAS to be somewhere that all the broken pieces can go, to be joined together again. As a general rule of thumb you should never have less than 10% free space on your hard drive. How much free space do you have?

After you have defragged you should be running an anti-virus program, an anti-spyware program and you might as well run an anti-rootkit program as well. Try this link (for all three):

http://free.grisoft.com/doc/5390/us/frt/0

There now remains 'bloatware' - after running for a year you may well have accumulated a startup that includes various unnecessary programs that are just sitting in the background (doing something you don't need) but using up processor power that you could use elsewhere. My weapon of choice is WinPatrol:

http://www.winpatrol.com/download.html
The download is beside the THIRD Scotty-dog down the page.

WinPatrol allows you to view lists of different groups of programs all running in your system. You should initially examine the 'Startup Programs' list - are there programs starting up here that you did not install? If you spot something you don't like, you should elect to [b]DISABLE[/b] it, rather than delete, because that way - if it turns out to be something you shouldn't have stopped - you can simply re-enable it again.

Also, download and install CCleaner: it removes all manner of detritus that will have formed within your system's registry over the past year:

http://english.ircfast.com/lv/group/view/kl25623/CCleaner.htm

After you have run the above programs, you should have a better running system.

Post back and we can try to help you further.

Good luck!