OK - serious feedback time!
Firstly, I think your main wrapper is designed for 800x600. Whilst this isn't major problem, you must bear in mind that only about 5-6% of people still ue this resolution.
You may want to think about increasing it to 1024x768 to get within the "fold".
The header image is nice but doesn't really say anything about web design.
If you want to keep a nice "light airy" feeling, why not try to use some royalty free photography, rather than this illustrator created image (which looks a bit cartoony).
Your ad in the right column isn't the same width as the links <div> which doesn't tie up.
Some of your text goes a little too small - try to keep it 11px or larger.
In your contact page, you should check the spelling of Advertising. In addition, try to split up phone numbers into sets of 4 or three: this makes them easier to read or input into a phone.
For a professional company, you shouldn't need to use of capital letters. On your services page for instance, saying much more on the extras page is a) too tacky and b) not really worded well. Its the age old story of not using "etc." If you have something good, then say what it is or just give an idication of something else, but don't use phrases like these.
You will find that people looking for web desing will be inundated with people trying to get their business. As a result, you need something that makes you stand out. What are your strenghts? No-one believes that any company will be good at everything.
Wat about something like.
Specialists in Search Engine Optimisation and thought-provoking unique designs.
On your welcome page, try not to give the impression it was done by one person. The phrase "Even this site was designed by me" makes your business sound small and insignificant. Try using "us" and "we". I know you've done this yourself (and you should be proud of that) but to attract business, you need to alter your thinking.
On your links page, you might want to give browsers an opportunity to submit reciprocal links. These will a) make your site more attractive to search engines and b) make your site more attractive to search engines. Did I say this twice? This is because your outward outbound and inbound links are very valuable for rankings.
Finally, and just being really picky, you could do with a nice graphic on your welcome page to give it some "ooomph", which it currently lacks. Can you use flash?
Hope this helps a bit more.
