Re: administrator account
It's a very much recommended 'best practice' to have at least two accounts with administrator capabilities, so that if one gets corrupted (and that happens!) you still can use the other to fix it.
And it's a not too well known fact that making any of your own user accounts hides the 'secret' administrator account in Windows XP, except in Safe Mode.
It's mentioned, for example, in http://www.mydigitallife.info/unhide-the-administrator-account-in-windows-xp/
As most users don't know that , and the account has no password by default (and if they don't know it, they won't change it either), it's a quite popular way to break in into a XP computer. My guess is that it works in 95% of the PC's. Microsoft made it safer in later versions of Windows.
So I'd switch to using the new account, and leave this one for emergencies. To be safer, give it a password and write it down somewhere so you can retrieve it if you need it 2 years from now. Surely the best practice.