A few hours. More, if by wipe you mean really wipe and not just reformat.

It should take around 1.5 hours, depending on the hardware speed and amount of programs, and the user.

Reformat and reinstall windows about 2 hours depending on the PC, software will take longer depending on what it is and how much you have :-)

I would set aside at least 6 hours if I was going to reinstall all my programs and documents, as well as the operating system. I'd make sure I had a book to read or something else to do as well while all those progress bars were trickling across the screen.

http://grownupgeek.com/reformat Doing a Format on Your PC Should Be A Last Resort! Reformatting your Windows computer is usually the absolute last resort and is often done unnecessarily. Before you go through the process of doing a reformat of your hard drive please take a few moments to read through the rest of our website. If you are reformatting to fix problems with your Windows computer it's possible that by using some of the tips on our site, or by downloading or purchasing some of the tools or products that we link to, you might be able to avoid the need to reformat your computer. Because doing a complete reformat of your computer will erase the contents of the hard drive and require you to reinstall all software, reformatting is usually a last resort. http://www.winsupersite.com/showcase/windowsxp_sg_clean.asp It's a hassle for a variety of reasons, but sometimes clean installing Windows is the best bet. This is doubly true of XP, especially if you were previously running a Windows 9x-based OS. The upgrade procedure works, and works well, but it still leaves your hard drive littered with the remains of the past, wasting valuable disk space and making it difficult to tell which files are OK to delete and which should be left alone. A clean installation of XP will also give you the best results, performance-wise. The downside, of course, is that you're starting fresh and will have to reinstall all of your applications, backup and restore all of your data, and re-do all of your personal settings. There are tools that will help you overcome these issues (see the pre-installation checklist below), but in some ways it's still a good idea to make that clean break with XP, especially for the 9x crowd. This is because XP is so different that you might want to spend time using it in its default set up. I suspect that many people won't want to change a thing if they just give it a chance. Here is the difference between the two that you asked for hope this helps and I know its long but thats just me I always give people lots of information! second site walks you though clean install also. both good sites.

The last two times, it took me about 15-20 hours over the course of a week. You are asking about MY computer and I have a lot of software loaded on here, much of it requiring configuration, and some of it (mostly anti-malware stuff) requiring downloads that take a couple of hours. Then there is the recopying of documents which takes another hour or two.

It will take time depends on the speed of the system hardware and program files..