which is better to help my computer run faster?

I had Pop-up Virus and I used Mcafee to clean them. It didn’t clean them well. Then I used Spybot. But I think Spybot deleted some of my system files in Window XP. I can’t boot my computer now. I have Dell reinstallation CD. But I don’t want to install the Whole Window and erase all my data and softwares. Some of my softwares, such as Microsoft Office, came with my Dell computer but I don’t have the CD to re-install them. Is it possible I can boot my computer and repair my Window XP?
Please help!
Thanks everyone! I’ll try your advices at home tonight.

I have read articles that suggests using registry cleaners to restore a system’s performance. However, I have also read a article in a Windows XP forum that says cleaning the registry will essentially degrade system’s performance rather than restoring it. How true is this? Dedicated for IT experts.

I have a HP Pavillion DV8000T notebook that i purchased from HP directly. The notebook is 13 months old and out of warranty. My hard drive failed and I will need to have it replaced. This is the second time my hard drive has failed (previous instance was during the warranty period) My options are:
(1) Use HP and pay 0 – this includes a new hard drive and installation of MS Windows XP Media edition. It comes with only 90 day warranty.
(2) Buy the hard drive myself – I have Windows XP software. I would have my office IT desk install the hard drive and the Operating System. Cost 0.
My Concern is:Will I be able to get all the drivers that I need to get the most of my machine. This is a high end machine but I am extremely disappointed with HP service. There is only a 90 day warranty on a 0 repair which represents over 33% of what I paid for the entire machine. Since the hard drive has failed twice already-I figure if it fails again, I will buy new notebook.

I am looking for a good registry cleaner for my x40 laptop, running XP Pro. I have done some research on google, Registry Mechanic and CleanMyPC Registry Cleaner seem among the best,

CleanMyPC Registry Cleaner http://www.registry-cleaner.net/

Registry Mechanic http://www.pctools.com/registry-mechanic/

Is there anyone who is using these cleaners can share your experience? Which one is better? Or any other recommendations?