Hotmail users...

[Nitros]

[X] Hotmail
[X] XP
[X] Internet Explorer
[X] Replying on Microsoft 'antivirus' measures
[X] Doesn't know not to click an email link they don't know about

= Not surprised...

I mean, I'm not trying to be a *Removed* or anything - so please don't take this as an aggressive tone - its hard to be firm without being too harsh when typing, but this will keep happening unless you understand why you got the virus. And other people may find it helpful.

Firstly, seriously - have you not heard just about every single computing FAQ/Teacher/Anyone-who-has-a-computer telling you not to open links in emails you don't know about? Its got no subject, and its just a link. Don't click it.
Secondly, get a decent browser. I understand you may not have the money to upgrade your OS to windows 7 - so that is forgiveable, but IE 8? You can't get IE 9, because Microsoft gave up on XP - so go for firefox/chrome/opera. Hell, even use safari for windows over IE 8.
Third, get some sort of semi-decent anti virus software. If it was Microsoft security essentials that picked it up before anything else, then you don't have one. Something kind nod32 or kaspersky would be good, but seeing as you havn't bought windows 7 - I assume you would prefer to go free - so grab something like Avast! free, or maybe AVG free. If your going to be clicking on random links, then there is a change these will stop bad sites (but I wouldn't reply on it)
Fourth, hotmail used to be great - but all of those crappy emails are the reason I switched to gMail. Since I switched (couple of years ago) I can count the number of spam emails I have had with one finger. Its just better at getting rid of spam.

Hope this helps.