umm what games are you going to be playing? in general I would say that 1680x1050 is going to be the maximum playable resolution for an 8800gt or 9800gt by my standards, I have a 9800gt and a 22 inch monitor and tend to play @ 1440x900 so I can have 4xAA.
The 8800gt is rather getting old.... It'll handle most games out there at playable settings up to 1680x 1050 i would say, but 1920 x 1200 would bring the 8800gt to its knees. I would stick with the 22" monitor or upgrade the GPU and to the 24" monitor.
I can't really afford a 24inch for $300-400, then $100-$200 on a new video card, yikes!
I'll likely buy the monitor at a retail store, maybe BestBuy, as I'd like to be able to return it easily for any reason if I don't like it. There's an 22" LG for $239 right now (10K contrast, 2ms..) that I will likely get. The 24inch version of same monitor is $399.
I've been on a 17inch, non-widescreen, 1280x1024 LCD for the past 4-5 years, the 22inch should seem MORE then enough for me.
It all depends on whether or not you demand to have AA and maxed settings. If you're like me, having a bigger screen is worth lowering some settings, and living without any AA, but I haven't had a current gen, high end card since...ummm.... ever, so I don't mind playing without maxed settings. Personally, anything that looks as good as FEAR is plenty good to me.
The logic being that a monitor lasts you far longer than a graphics card does, so it makes sense to cater the GPU to the monitor, rather than the monitor to the GPU. You might be mismatched for a little bit, but 1 year down the road you will likely have a shiny new GPU, but still using that same monitor, so you might as well make that monitor a good one that you'll enjoy.