I got my SSL Cert from instantssl.com too...it works like a charm...just not at TCH yet...I'm still waiting to have my account activated...
BTW...TCH can't have the trust logo on their shared ssl site because they can't garuntee anything for anyone other than themselves. You have to get the trust logo for yourself...and it isn't cheap...
The logo that instantssl.com is nice...it's primarily for eye-candy and the over-paranoid surfer. But, in today's day and age, it's not absolutly necessary to have a "this site is authentic" type logo.
You should examine your target audience. If you're selling specialty lava lamps, chances are you aren't going to have people, who are convinced the CIA is spying on them, buy a specialty lava lamp. Therefore, a simple privacy policy and statement explaining the transaction the user is about enter in to should sufice.
DISCLAIMER: If you are CIA - do not read this post...stop spying on me...and let me have my specialty lava lamp.