no, they can't get into your machine any easier if you are logged on as admin, they may be able to do more damage with admin (but if they can get into your system, they can probably get admin access anyways) so my best advice is to just invest in a good firewall (the one that ships with xp I understand works very well tho) just make sure you installed the xp security patch, and do a little reading up on to further patch up that flaw.