I have some suggestions for further development of your site.
I note them in the order of time they came to my mind
a) Do you really like these pop-up ads? For me they are bound to geocities and hypermart. Usually freely hosting horrible sites (or course there are also some good sites). These popups not only drive attention away, they also drive focus away (e.g. the mouse-wheel does not any more scroll the page). I find this extremely distrubing. Do you made good experience with these popup ads? Do many people come from other sites to your site? If many people are coming, please tell me and I'll consider placing these ads on my own page.
b) Main Page (index.html)
I'm using a 800x600 display which is more or less the screen resolution used by most people. At this resolution in full screen, I can just see a few images. Once I made an experience with a friend who never scrolled down (I had to teach him). I think that most people just don't notice the scrollbars and if they don't see something in the first page of view, they don't see it at all.
If you look at nearly all large sites on the web, they have a lot of important things on the main page of view. They transfer the message, they have the master navigation there etc. A very good example of this is www.msnbc.com
where each news you can read is interrupted at around pixel 600 with some ads and another naviagion. Only if you continue to scroll down, you can read the whole news article. But everyone sees the few main lines. They also placed a link called "Complete Story" on that page, just to move the browser down to the start of the story. It seems that most large sites find that web surfers are extremely stupid.
For my own pages, I never make it that strong. I'm just looking that the main message and contact information is visible in the first page of view (and of course the ordering possiblity). Many info is only available while scrolling down on my site, but I hope that everyone can find what he needs even if he does not scroll.
I only found that problem with your main page and your pricelist page. On the main page, I would ensure that one could navigate to the pricelist without scrolling. And on the pricelist I would ensure that contact information and that nice "CALL ME" field is visible. Everyone should be capable of getting in touch with you then.
On some pages, you have a small dark-blue table with white text. Maybe you can place one of these small tables in the top left of all your pages with a short tagline and the "CALL ME" button and your email address.
I don't know much about your business, so I'm not sure how to write a short tagline, but I'm sure you can do so
I really like your idea of having different contact possibilities on most pages. One reads "Send me mail" one is "Call me" one is "Send me a fax". I feel that while browsing your site, everyone finds "his" way of getting in touch with you. That's very easy to understand and good made. Unfortunately, I don't want to call all visitors to my site or even send them a fax. So it's nothing I could do on my own page. Great idea.
I like your colors and find the page easy to read (that's very important, ever tried to read a page with dark blue letters on black background ???)
Greetings from Bonn, Germany