12ms should be fine for a monitor, however 8ms is ideal.
I'm running an LG L1717S 17" 12ms LCD and it's fine on all games (including BF2). No ghosting what so ever. But if you've got the money (which it's clear you have) then go with the 8ms just to be sure and to keep everyone here happy :P
As far as gfx cards go, The ATI X1800's are supposed to perform the same, if not a SLIGHT bit better than the 7800GTX's, however the cost-performance ratio is extremely low. The best "bang for the buck" would definetly be the 7800GTX as ATI have enetered the market fairly late on their new cards, therefore have suffered the consequences of high retail prices. You see a fairly large price drop in around the christmas/new year stage.
Intel Core 2 Duo E6400 *Cooled with Thermaltake Mini-Typhoon* || Intel Quad Core Q6600
2gb Kingston 667 DDR2 RAM || 4gb Kingston 667Mhz DDR2 RAM
Gigabyte 512mb 8800GTS (683/2150)
250gb Seagate HDD (ATA133) 7200rpm/16mb cache || 750gb SATA2 Seagate HDD
ASUS MW221U 22" Widescreen 2ms.
Logitech Z-5500D 5.1 Speakers
Creative X-fi Xtreme Gamer Fatal1ty edition
3DMark06 Score = 8524 (1280x1024)