The Main CSS Question?

Ok first off I'll happily admit that I've went and made a bad design decition when starting my webpage, At first I was totally focused on functionality and only very basic layout, but now that I'm nearing the end of my functionality I've started looking closer at my CSS Design and I've came accross the main CSS question......and that is what kind of screen resolution should I build my site for?

I want to favor to the majority of people and the last survey that came out said the majority of people are using a screen resolution of 800x600 pixals, however I also believe my site is actually for more intermediate computer users with a screen resolution of 1024x768 pixals so I could build it for a screen resolution of 800x600 which would also work for the 1024x768 resolution but I also want the users with the 1024x768 screen resolution to view the page on full screen and not have the white spaces...

I do not like using Percentages I woud rather set my items in pixals, I've found that percentages dont have the level of accuracy that pixals do, so what I thought I would do is build two different CSS Classes one completly for 800x600 and another for 1024x768 and have a kinda pre-entry to my website where the user can choose which screen resolution they want to view the site in...

So my question......Is it possible to do this, I am a bit unsure of how I can set up a button so when clicked the CSS for that resolution is set....here is a bit of an example of what I mean

User 1 comes to the site, see's a screen that says please pick a resolution, they pick 800x600 and continue on to the site viewing it perfectly in full screen, now user 2 comes around and picks 1024x768 resolution and instead of calling the 800x600 CSS Classes it calls for the 1024x768 classes to be used...

You can do that. Or you can design so that it doesn't matter what the user's resolution is. You might look at the Themes and Skins options.

Jeff

Yeah if I can design it so it doesnt matter what the screen resolution is would be perfect I know a couple possible way's to do it, basicly have some containers with percentages and have the content within those containers pixels.....but I will definatly look into the Themes and skins option as well...

Thanks.

Here is what might be a dumb question but I'm still going to ask it, just because if there is a way to do it... Then my life becomes a thousand times easier right now....by any chance can you have your webpage programmed to detect what kind of screen resolution that the user is using?.....

I know you can detect there IP Address and a whole lot of other information so I thought I would ask...