A few recommendations for the home page:
1. Fix the copyright date in the footer. Don't hard-code the date. Use php to present the current two digit year in the format 2010-11.
2. Allow users to login via social networks: twitter, facebook, google, msn, etc. Place the icons next to the "login" option.
3. Add more social networks. You currently offer twitter. Add facebook and google+ to your home page.
4. Add more social networks to your product pages too. I noticed you offer fb Like's next to each product which is excellent. Add twitter and google+ there as well.
5. Add trust symbols. Versign, TRUSTe, BBB, MasterCard SecureCode, Verified by Visa, etc. Take a look at the bottom of the vzw.com page. I like my sites to have a similar look to their trust area. If you are on a limited budget, skip TRUSTe as they are way overpriced. All other trust symbols are about $375 each for unlimited views. TRUSTe is $500 for 100 views and $1000 for 500 views. It is definitely worth it for any large e-commerce site but smaller ones may wish to skip it.
6. If your URLs are ever changed, drop the ".html" or any other tech extensions. The remaining URL is short, looks nicer and will not need to be changed due to changes such as moving from html to php pages.
7. Along the same lines as #6, your current pages contain an extra id information which you may wish to consider removing. An example URL is: http://www.gear-zone.co.uk/sports-tcid19.html. The URL would look much cleaner as http://www.gear-zone.co.uk/sports
8. Consider accepting PayPal and Google Checkout as payment methods. PayPal is the world's largest online payment processor. Google Checkout allows any fees you pay for payment processing to be credited to your AdWords account, so if you use AdWords you basically get free payment processing.
While there is no evidence to support Google gives any direct ranking boosts to sites which use Google Checkout, I believe there are some indirect boosts because it benefits Google directly and because they know more about those sites and can trust them to a higher degree.
Good luck!