Computer Registry Cleaner?

I just bought a ew Dell Computer (Windows Vista) and I had a "Registry Cleaner" that I had bought from me old computer (Windows ME version) and I had installed it on my new Dell computer. Well I scanned my computer and there were like 21000 problems that the Registry Cleaner detected on my new Dell computer. My question is was I wrong for installing this Registry Cleaner on my new Dell computer and the problems that were detected may not really be a problem. I do not want to destroy any important updates on my computer. Please help!!!

I am planning on selling my Dell Computer that has windows xp installed. I have had this for about an year.
My question is, since all these days i had so much of private information on this computer how do i delete all of the files so that they never can be retrieved.
If i just delete files and sell the computer, files can be recovered. The only way they cannot be retrieved is if i do a format or even better low-level format. However, i do not want to mess up my existing windows xp and other other softwares.
Which leaves me with only one choice. Delete the files "somehow" so that they cannot be retrieved.

Hope i made my query clear.

Thanks in advance.

Hi guys,
I have a Dell computer that I have had for a couple years. It works great but I have low disk space. I have uninstalled various things and need some tips and ideas of how to clean it up. I only have 1.5 GB of free space on Local Disk. My Capacity is 28.6 GB’s.

Thank You!

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've been getting a blue screen with the following message: Run a system diagnostic utility supplied by your

Try changing video adapters. Disable and remove any newly installed hardware and drivers.
Disable and remove any newly installed software.

What does all this mean?

My computer has been very slow lately and I ran disk clean up and did defragmentation yesterday. However, I'm still getting blue screens.

How can I fix my computer? Would you please describe step by step the whole process.
Thanks.

P.S. I have a Dell computer, a windows xp