Case= Antec 1200
Motherboard= Asus P6x58d
CPU= i7 920 @ 4ghz With prolimatech mega shadow with scythe s flex f push pull
Memory= Mushkin Redline 6GB 1600Mhz 6-7-6-18
Graphics Card= 2xSapphire Radeon HD5870 Crossfire
PSU= Rosewill Bronze RBR 1000Watts
Hard Drive= 2xSeagate 7200.12 1TB Raid 0
CD Rom= Sony Optiarc DVD Burner with LightScribe Black SATA Model AD-7241S-0B LightScribe Support
OS= Windows 7 Home Premium 64 Bit
Monitor= Asus VH242 23.6" 1080P Monitor
Either of these would be vastly superior to the Rosewill. 850w is more than enough to run what you're looking at. Keep in mind the Antec is a large form factor, but it's a rock solid PSU that was built with the 1200 in mind.
Don't go cheap on your PSU when you're putting top quality parts around it.
Might consider Win 7 Professional as it's the lowest tier that supports XP mode. If you play legacy games it's all but a must.