Hi, I found this through Google
How to remove IE7 - REW Thomas's Blog - REW Blogs Real Estate Blogs looks its just what you need..

Bugger! sorry I should have read it properly first.. Back to the drawing board
I have been checking through some sites and it does seem doubtfull if indeed it can un-installed. Apparently its quite an integral part of Vista. I did find this page though which could be worth reading and it does actually give you instructions on how to remove it.
Release Notes for Internet Explorer 7
It goes on to say that you have to type this in your 'Run' box and it will un-install..
%windir%\ie7\spuninst\spuninst.exe I did try it but with not much luck, maybe more reading is required. Hope this helps and good luck.