It would be advisable to look at what CNet has to offer in the "downloads" on the CNet Tech Sites drop down list.
I personally use "Registry Mechanic" which comes highly recommended.
My notebook runs XP Home for about a year and 1/2, and with the increase of spyware, adware attacks, the computer now runs awkwardly, though its main function is OK. I suspect that it was I who disturbed the system by changing registry values deliberately with ad-aware, spybot, and system mechanic. For example, my internet explorer 6 SP1 often goes haywire like "goes to CNET while I search Google". So, I am now in need of a VERY GOOD registry repairer and "maintainer" which WILL NOT cause any further problems. Can anyone (or professionals) suggest the BEST registry fixer downloadable from Internet? If there isn't, try "buy-able from stores".