Using IE8 with NIS 2005

I have Windows XP Home Edition on a four year-old computer (HP Pavilion dv 4250us Notebook) with 504 MB of RAM.  It has pre-installed versions of NIS 2005  along with IE 6.  I was wondering, if I were to install IE8 and Windows Live Mail, would I still be able to use NIS 2005 with, at least, IE 8?  I am starting to doubt that NIS 2005's anti-spam feature would be used with Windows Live Mail because the latter has its own filtering system that separates spam from good e-mail.  Please help before I decide to make changes.  I'm anxious over the technological changes. Thank you.