Configuring IIS 5 with multiple IP's for SSL to work - at wits end!

Hi,
Ive run into a small problem recently that is holding up my new clients website. Ive been hosting a main site on a server with two ip's. I installed a comodo SSL certificate around a year ago. Just recently i needed to install SSL on another site that is hosted on the same server. I was told to purchase an additional IP which i did so that the SSL certificate would work with the site. The problem Im getting is not knowing how to tell IIS that the new site im trying to install ssl with is registered with its own unique IP. when i go to;
(https//originalsite dot com) - the one with ssl first installed, and domain registered as primary domain on server
all is fine, when i go to;
https//any other site on my server dot com
all sites hosted on that server when typed with https: come up wtih the originalsites dot com's certificate. I believe this is because it is registered as the "primary domain" in the servers matrix panel. This is even though i have go through the properties>securiy etc.. and fully installed the new SSL cert to the New site.
If ANYONE could please give me instructions that a child could understand! on how to assign the new IP (ive already registered to my network card, so that it appears in iis options) so that all http and https requests point specifically to that ip. Note: when i attempted to go to the properties of the website and "assign" the ip address in IIS, or even assign the ip in my matrix panel it doesnt help the certificate problem above.
Many, Many Thanks in advance!
G

What version of IIS and windows?