Just took a look at your home page using Firefox and your menu is hidden behind your Flash animation so unavailable to those 11% of visitors who use Firefox. Ok, I accept only 11% but it's growing.
A couple of thoughts...
When you say "improve the website conversion ration" you don't mention what it currently is? On my gifts site I'm happy to aim for a conversion of between 2-5% so 95-98% of visitors (ruling out all bots, etc) view without buying but I think different markets are likely to have different conversion ratio expectations.
Things I'd be looking at in your situation would be
What's the pattern from visitors (are they only viewing your home page and not perusing (nice word)

generally over the site?) Which might suggest a few things.
Are you noticing (and discounting) all bot behaviours and any other rubbish so that you are looking at ONLY the actual true visitor instances and then doing your conversion reckoning after that?
You've got a fair few images in general across the site, have you run all of them through a dedicated image optimiser program and not merely what Photoshop etc churn out by default?
Flash file size (could you reduce it?)
Also the images on your home page total well over 100kb (without counting the Flash file) so folk on an analogue modem might not be hanging around.
Have you looked to see if your visitors are in fact downloading ALL the relevant files for your home page as doing so might lead you to conclude that they're leaving before the full page loads.
One other thing, it might be that you're getting loads of passive visitors who are just curious about your product as a result of an energetic push for affiliate and other links.
There's also the fact that you're selling what really is one product and although very original and quite unique in the UK and Europe it still is essentially 'a product with personalisation' which in itself could limit your conversions. It's possibly got as many disadvantages as advantages.
Lastly, do something so that you get as many bites at the search engines as you possibly can and whatever your conversion rate it can only bring more profit as more visitors find the site.
Apologies, only had chance for a quick look and am just throwing oranges in the air for you to think about. Others will add their bit I'm sure.
Ray
