Until relatively recently, due to the US Government's policy on exporting encryption software (they consider it to be munitions, and therefore a potential threat to US security in the hands of its enemies), the encryption built into UK and International versions of browsers has been relatively weak. If your browser has this weaker encryption (known as 40- or 56-bit, usually indicated in the help/about info), you may want to consider upgrading your browser to stronger, 128-bit encryption, even though it's probably secure enough for most data. To do this, you could download an updater program from http://www.fortify.net/ which will give you full-strength encryption.

However, most of the latest versions of popular browsers now incorporate the stronger standard, so you could just download a more recent copy. This is highly recommended, as this will also fix any security flaws that may have been discovered in your older browser. You can check the level you are using by accessing a secure page, then choosing Tools → Page Info in Firefox, View → Document Info in Netscape/Mozilla, or File → Properties in IE6, or Page → Security Report in IE7.