Reformatting Hard Drive and Reinstalling XP

So awhile ago I had this virus, or something, that was messing with my internet connection.  I decided that this was a good excuse to clean things up, reformat the hard drive, and reinstall WinXP.  Since doing this, I've had all kinds of trouble.  Everything from problems with my laptops standby mode (the computer would just become unresponsive when coming out of standy) to my hard drive not being completely wiped.  I've since done both a repair reinstall and another complete reinstall where I repartitioned and format the hard drive.  Everything seemed fine then for a day or so, then I started getting some kind of fatal error when I reached the Windows desktop.  I believe it claimed an RPC (or something...) file failed to load and windows needed to restart.  It would then do a minute countdown and restart my laptop, only for the same thing to happen again in an endless cycle. 

I've been in contact with support people, but haven't been getting clear answers.  One email actually told me to buy a new hard drive from them.

What I'd like to do is completely start over.  I'd like to reformat everything, probably using a boot disk I guess and completely cleanse my hard drive.  I'd like to then repartition the space so that there is one large partition so I can take advantage of all my hard drive space.  I noticed when reinstalling before that there was a small amount of unpartitioned space and also another very small (8 MB) partition that wasn't part of the large main partition XP was installed on.  Once I have the whole thing clean and partitioned, then I'd like to put a clean copy of WinXP on the drive.  

My main question, is how do I do this?  I've been reading some conflicting info and am a little confused.  I want to make sure I COMPLETELY clean the drive this time so I can make sure everything works correctly (like it used to...) when I get things working again.

Thanks!