tunesBag design - fluid vs fixed width: Your opinion matters

We're working very hard on finishing the next release of tunesBag and one nasty question at the moment is what should be the default design width - fluid vs fixed.
In the past it was much easier ...
In the earlier times of the web this was no big deal as most users where using a screen resolution of 800x600 so every website has been optimized to this screen size.
Today I can see the following data in Google Analytics, however:

• 1280 x 800: 26%
• 1024 x 768: 22%
• 1280 x 1024: 17%
• 1440 x 900: 10%
• 1680 x 1050: 9%
• ...
• 800 x 600: 1%

I am using two resolutions, one time 1280x800 when I'm using my MacBook without an external screen and 1680x1050 with an external screen. A website that always looked crappy on the big screen is Facebook, just too much white space around (does not mean that they should place ads everywhere just to fill up the free space ;-)).
Your opinion?
So please let me know your thoughts on this issue; below you can already see a screenshot of what it might look like. Fluid definitly reminds me of an "application", not sure if this is the way to go.
Of course it will be no problem to switch between the two versions using a skin but there has to be a default style.
Post your opinion here or in the Google Group
The best way to talk about this decision is to talk about it in our Google Group - so join today!