Congratulations Mike - that's a great first attempt (and CSS is definitely the way to go!)
Constructive criticism:
I'm no big fan of your color scheme to begin with, but for me what makes it REALLY not work is that your logos (e.g.
http://www.spacecityairbrush.com/test/sca5chrome.jpg) were obviously made to be displayed on a white background... They look wrong on bubblegum flavored backgrounds.
"Houston Texas" is dropping right down into the border...
What's up with weird question-mark-in-a-diamond symbol in your About Us section (i.e. "Children�s" instead of "Children's")?
Navigation links in a row at page bottom is a good idea... but it'd be much better to space them out and/or put bullets between them. Use "" to insert extra spaces between Samples About Us Gear Pricing Gallery Contacts and Home... Otherwise The Words Run Together And Are Unintelligible. "•" is a pretty handy bullet symbol. (Put a semicolon after it when you use it... it will look like this: •)
Your use of photos is excellent. I'd consider making the photos enlargeable (because they're just thumbnails. I wanted to click on them and see larger versions.)
Frankly, your writing style is very understated... and I'd recommend you consider making it more direct and active if your ambition is that this website should increase sales. You're emphasis seems to be on simply informing the general public that you've worked in the past. Use "words that sell" and emphasize the BENEFITS you will offer the reader. Speak right to them like it's just you and them. (Use the word "you" a lot.) Consider moving "About Us" to the bottom of the first page because that section is all old news.