There are three components to consider when purchasing a SSL security certificate.

Security - What level of security are you purchasing?
Compatibility - Is the SSL Certificate compatible with major browsers?
Price - What is the price of the security certificate?

SSL Security Products Article Continued....

Article written by Dan Kennedy (MonsterCommerce, LLC)

Just a quick side note. All of the certs we acquire for our use and our customers use 1024 bit keys. In a nutshell, our certs our 1024 bit capable and support 128 bit browsers.

The strength of the public key in the certificate is established when we generate the key pair for the site in question. We generate a 1024-bit key pair and submit the associated CSR (Certificate Signing Request) to Geotrust, and then the certificate returned contains the 1024-bit public key. Should browsers support higher than 128 bit encryption, the cert is effectively "scalable" to handle it.