So, I've been saving up some cash for the past few month, and I intend to do some upgrading in the near future. I've narrowed it down to one of three things, but I wanted to get some opinions to help me in my decision. I know that there will be a bit of a price difference between the options, but that's not a factor. I use my computer mostly for gaming, then home theater, and basic internet stuff. First, my current setup:
1) Windows 7 64 Professional - I haven't been very fond of Vista since the day I installed it, and I would like to go 64 bit.
2) Second 24" monitor - Quiet often I find myself wanting several apps open at the same time. I'd have to buy a bigger desk though...
3) Two 5850s - Selling both of my 4870s & the coolers would yield enough $$ for one card. Plus, dx11.
the Windows 7 upgrade will probably be the biggest overall improvement to your computing experience. It is light weight and versatile enough to run well on anything from a gimpy netbook on up. The tab and task bar management is better, so you can have improved multitasking without a second monitor for the mean time. Also, by going to 64-bit, you'll reclaim that half gig of memory that's unusable by your 32-bit OS currently, helping performance a bit.
The 5850 is going to be a great card, and a very reasonable upgrade, though I don't think you'll find much benefit in putting 2 in crossfire without a more significant overhaul in your system, especially at your current resolution.