I got the error response when trying to register with salesforce.com "...Please connect securely to salesforce.com using a browser that supports 128-bit encryption"

That site uses an AES-256 (256 bit) cipher to connect.

https://login.salesforce.com/

Which security software (firewall) do you have?

Do you have a firewall that might block secure connections?
Did you check the settings in the firewall?

Des this site work: https://www.fortify.net/sslcheck.html  ?

yes that site gives AES cipher, 256-bit

I use Kaspersky antivirus Internet Security and standard Vista brandm. i disabled both but same result

This worked for me. From Salesforce:

"Your link is HTTP, someone turned on the "Require HTTPS" flag in the security settings for your organization. As you're not using HTTPS you get the error message. You can update your shortcut to use HTTPS (or look at more secure ways of managing users credentials, having credentials in plain text is a security risk)."