usually helps to change password if you suspect you've opened a mail that grabs your password.

Be careful next time.

I don't know how robust live.com is, but most of the cases I saw of spam sent via yahoo.com (common thing) was spoofing, not hijacking the account.

But yeah, changing the password AND running a malware scan of your PCs usually helps.

I suggest using Live CD/Live USB feature provided by Dr. Web, which, due to its nature of being run from a boot device, is almost impossible for malware to defend against. (The only exceptions would be things which flash themselves to your PC BIOS and the like, but that's... Well, not exactly common and lately, hardware is built to protect from attacks like that.)\

http://www.freedrweb.com/liveusb/?lng=en
http://www.freedrweb.com/livecd/?lng=en