Aww, come on now. You know that the only reason that there's nothing really wrong with XP. Even nowadays. It's still perfectly viable for most things. Except MSN, apparently.
Yup, perfectly viable at being a [censored] mess from a security standpoint. Everyone runs as administrator, created a multi-user environment that promoted everyone to run as administrator, No ASLR, gimped firewall, IE integrated deep in the kernel (causing both security and technical problems, and the reason why IE for XP has unpatched security holes AND cannot be upgraded to IE9), and plenty of other things.
XP is the bane of modern computing, because XP isn't modern computing.
On the subject of the OP, rather than using the crappy default client, why not try a third-party client. It'll also get rid of the ads too.
http://www.amsn-project.net/
http://blog.emesene.org/
http://www.pidgin.im/ -- not as feature rich for MSN, but is a multiprotocol client.