I won't partake in the livlier discussions under the thread How should SSL be priced? on this same forum; I will share my experiences with you.
I installed 2 QuickSSL certs on a server, and they are trusted by IE6, 5.5 and an old version (4.76) of Netscape. However, in the IE machines, if the option "Check for certificate revocation" is checked (the default on my Win2k machines), both QuickSSL certs give a warning "Certificate Revocation Information is not avaailable - do you want to proceed?". I contacted Geotrust Technical Support, and they had the same thing. They were not able to provide me with a solution. Yet, a 3rd QuickSSL cert issued a few weeks earlier works fine on all the above browsers.
I installed an InstantSSL cert of another server, and it works perfectly on all broswers, no warnings, does everything right.