Much depends on what sort of problems you have. And any programs, (freeware, shareware or paid), that suggests you have 60-70 problems would be suspect to me.
You can get Registry Cleaners, (not for the faint hearted), that are freeware and can do a good job if you are careful and know what to delete and what to leave, but with Windows XP registry, problems do not manifest themselves as much as they did in Win9x or ME.
Much better to use a combination of good house-keeping, windows updates and anti malware to keep your system clean and running smoothly.
Anit malware = firewall, anti-spyware, anti-virus and anti-adware. Keep the anti-spyware anti-virus and anti-adware definitions uptodate, and scan regularly.
House-keeping = error check the disk regularly, (once every 2 months or so), defraging if needed.
Keep WIndows updated.
Use Firefox instead of IE. Use Thunderbird or another email client instead of OE.
Don't open emails from senders you do not know, and be careful where you surf.
Mark