Basic guidance requested

Hi,

After two weeks of flakiness my game puter died last night.   It lasted 5 years so it's hard to complain but a new puter wasn't in my budget for this year.
Been looking at the various builds here and am getting frustrated trying figure out what I need. So I'm asking for some advice and guidance.

Usage:
 99.9% will be games

Type of Games:

 My Favorite Games:
   Simcity 4
   Silent Hunter 3
 Games I play alot:
   Games by Paradox Interactive like HOI3, EU3, Vicky2, etc
   Pride of Nations and other games by AegeoD
   Games like SPWAW, and World at War
  
 Play occasionally and like:
   Flight sims, CIV4, RTS type games
 Games I would like to play:
   Rise of Flight looks like fun. I would like to try some of those online games I read about. Who knows, maybe I'll like them.
   Not really interested in FPS type games but might like to try one or two just to see.
Special needs:
   It gets hot in this house. The normal summer temp in here is 78-82 with the puters turned off. Much higher when they're both on.
Screen Resolution:
   It depends on which I plug in.
   #1 1920x1080
   #2 1360x768  This was the TV, lousy resolution but has a 25" screen. I might slurge and get a Dell U3011, it's reccomended here
and 30" screen.... WOW. At the higher resolutions I would need a larger screen.

Budget:
 Have $4000 available. I would like to spend around $2500, not counting a monitor, but am fairly flexible.
Questions / Concerns:
 1- Recovery Disk: Have three ABS puters and all have been 'recovery disk hell '. If I can get the disk to even start it can take 6 to 10 trys
to get everything to install. Has anyone ever reformatted their DS puter? If so, how was it?
 2- Ports: When I got my first ABS puter I was shocked that it didn't have a place to plug in my Forcefeedback joystick. I learned to ask about plugging things in.
What can be plugged in and how many?
 3- SLI: All three of the puters were built with SLI and the intention to add another card later........ Yeah right, that never happened and the the games I played seemed to have cared less.
Do I need SLI for the games I play and the ones I want to try out?
 4- Upgradeability: All the rigs DS has posted mention this. It's been my experience that real upgradeability depends on the case. This puter, a Tsunami Dream case, is a breeze to work in. One of the other puters is a PITA.
How are the DS cases. What would be reccomended?

I'll be buying a puter this week from DS and am looking for some thoughts on what to look for.