As a web design firm it is a VITAL CRUCIAL part of getting jobs is to be able to have your design to be cross browser compatible. IE6, IE7, FF2, FF3, Safari and Opera should all be supported without question. Limiting your possible clients by excluding IE6 users is a bad idea. There are still many, many, many IE6 users out there.
Other than that you’re design is quite nice. I disagree about your menu order with the previous poster. I think you’re order is very natural and how you see it in most cases.
I DO think that you should include some portfolio imagery on every page. Maybe a random image show on every page.
Also the grey text on a grey background may not be the best idea. It can be hard for some users to see. I would recommend upping that contrast a bit.
On your services page – I think the drop down with your services should be a little bit more "dressed up". The drop down menu action is quite nice, but I’m not quite sure it fits. Maybe you should have blocks go horizontally across the page, and when clicked on they can then expand vertically next to eachother? Does that make sense? I’m not quite sure you actually want to hide those services either behind the dropdown action because people want to see what you do RIGHT NOW, they don’t want to have to click 4 times within the page to see what you offer.
The only other advice I have that has nothing to do with design/code is once piece of copy on the index – "Need that edge over the competition?" You ask the question, but don’t deliver how or why you will provide that edge.