Much helpful advice from forum member. As mentioned, the keywords tag is completely ignored by Google and only used as a spam signal by Microsoft, you would be better to trim those down to a few words per tag, for the minority places that do use them. The point on overuse of keyworded content also worth note, more so now than in the past.
Again as above, title tags. descriptions etc. need work. The Webmaster Academy a great place to start, you might also:
Along with reading through http://googlewebmastercentral.blogspot.co.uk/2010/03/googles-seo-report-card.html
Another issue with your website is the confused indexing, pages under both:
You also seem to have a duplicate of the home page:
Other pages indexed which are 404 (not found. Some may be recently deleted, you probably also changed page names (URLS) when you changed system. You need to 301 redirect from the old to the new for any URL change, ideally any deletion. A few of the old pages look to still be around, worth the time.
Recommend you take a look at:
Your website is on an Apache server, so you should be able to use a .htaccess file. Do not rely on control panel redirects, there's a guide to htaccess linked below and a useful coding page to save you time:
All the above will help get your site to a condition where search engines (and users) can understand better. You then need to look at the site itself:
One issue is inbound links. Most of what I can see come from link exchange, including sites that are highly active in that pursuit. Small scale re your website, any form of penalisation is unlikely but the links may have been devalued. In any event, I would remove the exchanged links from your site and have them removed at the other end if you can. You then of course need to consider how they are to be replaced, which leads us to content.
Adding unique and valuable content beyond your products might give people a reason to link and in any case, will help with search and make the site more interesting for visitors. Whatever you feel comfortable with that would really interest people and is relevant to the site.
You also need to sort out display issues. Mainly CSS problems I imagine, try your site in different browsers e.g. Google chrome, although there are some issues in all browsers.
Next thing to consider is how you are selling products. Is everyone going to email you to arrange this, or would you be better to be able to sell directly from the site. People expect this now. With a small number of products, you could just sort out a paypal account, or similar elsewhere and add buttons accordingly.
If you don't want to get too involved with much of the above, another option is to use a ready made ecommerce facility of this type:
Still not ideal, higher cost than standard hosting and you are not entirely in control of the site but worth a look. You could also consider moving to free ecommerce software, such as zencart, or magento. They have plenty of free/low cost templates and many factors are built in for you. They do still however need a fair amount of technical input to run well.
I don't use software of the serif type, so can't comment but also worth investigating what plugins, other add ons are available for that.
If you decide to stick with your current set up, enough above to be going on with for now. Just getting the basics organised and giving Google a little time should make a difference. If I were forced to pick, the mixed up indexing would be an absolute priority but other work will also be valuable.