The short answer is 'no'. The Windows system is much too complex, and the number of variables too great, for us to give you advice that will give reasonable assurance that everything you might reasonably want eradicated from a System drive will indeed be erased.
The longer answer assumes that you have moved or backed up any data you want to keep and depends on what you want to do with the drive. If it is staying in your possession (or the possession of someone you trust and who has limited IT skills), you could run CCleaner (with the overwrite option set, to get rid of as many as possible of those hard to find logs, caches etc. as you can, then erase all of the contents of My Documents and any other folders that might contain sensitive data (including your email store), uninstall all applications and remove any remaining traces (e.g. in Program Files) manually, and then run a free space erase (before you uninstall Eraser, of course!). If you work fairly hard at that, the likelihood that the new keeper of the drive will be able to get at sensitive data is reasonably low. Of course, the story would be different if the drive were subjected to a full forensic examination ...
A more secure answer (and not necessarily that much less trouble) would be to reinstall Windows from scratch (that is, with the drive being formatted). You'll then need to install any necessary Windows updates (including Service Packs) and drivers, then install Eraser and run a free space erase. If you have another machine and a suitable hard drive dock or caddy, you could improve things even further by taking out your drive and connecting it to the other machine as a non-system drive, quick formatting it and running a free space erase before reinstalling Windows. In the latter case, the drive would, in my opinion, be secure against almost any adversary.
Just as I read this through I realised that I had not answered your specific question (though the above advice remains pertinent). The easiest way to erase multiple folders is to select them in Explorer and initiate the erase from the context menu. You may fall foul of permissions issues, though this is less likely in XP than in Vista or Win 7.
If you are able to tell me what you want to do with the drive, I can probably offer better targeted advice.