If you bought it "used, from a company", do you mean that it was previously in an office environment? It might be set up to connect to a domain, which you are not part of.

Right click My Computer...

I've always been partial to Partition Magic, at least on systems up through XP. It allows you to resize all partions, essentially taking space from D and adding to C, moving the files as needed.

If you want it in the "like new" condition, you will have to format and reinstall the OS, because once you start using it, stuff gets added.

If you're concerned about removing any traces of files...

Control Panel | System

Or right-click My Computer, Properties, System Restore tab

Cobian Backup (http://www.educ.umu.se/~cobian/cobianbackup.htm)

The Read Only attribute has no meaning or effect on folders, ignore it.

Your problem is permission - are you running an account that has administrator privelege? You might try taking ownership of...

Spybot also has such a feature.

They don't identify every registry change - you'd never get any work done if that happened. They generally indicate when some program being installed/updated...

Is that CD actually an XP install disk with SP3 included, or just the SP3 update?

Partition Magic is another good tool for this. $$

Caperjack, sounds like BelarcAdvisor (http://www.belarc.com/free_download.html)is what you want. It details the hardware and software in a system. And it's FREE.

Not necessarily - he might have just installed a lot of crap.

What's your budget? I'd expect most such products that work over the network will be commercial, that is, $$$ products.

I use Belarc Advisor for personal purposes. They make a network product,...

Start by looking at what's in the Startup menu - delete what you don't want.

If you're handy with Regedit, you can look in
HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run
and...

roaming profile; network login, basic security?

Are you looking for the name of a specific system, like Novell Netware, MS Active Directory?

First, if you have a separate video card, make sure it's seated correctly and that all cables are tight. Has the computer or monitor been moved recently, that might have loosened or broken a...

Here's the Microsoft Product Key Update Tool (http://tinyurl.com/d73ep4)