ASUS P6T6 WS Revolution is for Workstation more or Servers and I would not get it unless if I need to have a server. It is not intended for Desktop PC but more for server/workstation. Notice "WS" (Workstation). Maybe it could also be use as a Desktop PC (I am not so sure about this).
While ASUS ROG Rampage II Extreme is classified as "Republic of Gamers" motherboards which focus more on overclocking and gaming. Personally, for me it is more like a marketing hype by ASUS because in the past, even models like Biostar TPower I45 broke the world's overclocking record and beat ASUS ROG Maximus II Formula. Before the arrival of Nehalem system, "Formula" stands for ASUS ROG motherboard that uses DDR2 RAM while "Extreme" version uses DDR3 RAM fro ASUS ROG motherboard. But with the Core i7 X58 Nehalem motherboards, they would all use DDR3 RAM except for Core i5 P55 Nehalem motherboards which could be compatible with either DDR2 or DDR3.
Anyway, you don't really need ASUS ROG motherboards just to do gaming on PC because they are very expensive high-end/enthusiast level motherboards. ASUS P6TD Deluxe or ASUS P7P55D Premium (one of the only P55 motherboards supporting SATA 3 and USB 3.0) is enough.
ASUS P6TD Deluxe is slightly newer than ASUS P6T Deluxe V2 and it has Xtreme Design with Xtreme Phases. Xtreme Design is ASUS's response to Gigabyte's Ultra Durable 3 and it is about using the best high quality components like all solid capacitors, etc for the motherboard.
Yes I know but I also would like to recommend him cheaper LGA 1156 motherboard. What if the OP is still a newb/noob and risking to get an unnecessary too expensive high-end Core i7 system? Obviously, you better tell him many things. Core i7 860 and Core i7 870 are also good on Core i5 motherboard. Maybe Core i7 920 might be replace by Core i7 930 or by a much more expensive Intel Gulftown which would could cost $1500 just for the CPU upgrade and that is just bad for him. Core i5 system (LGA 1156) seem to have more cheaper CPU upgrade path than LGA 1366. LGA 1366 is more for servers than for Desktop PC, those who bought Core i7 920 are those who bought it in the early 2009 when Lynnfield Core i5 wasn't launch yet. High-end Core i7 X58 system is more like marketing hype by Intel because it should have been only for servers and not for desktop PC. Seriously, who the heck would spend $1500 for future CPU upgrade or upgrading to something very expensive like 6 Core Intel Gulftown CPU???? 6 Core (Hexa-Core) is very unnecessary and overkill for Desktop PCs but it could be useful for Servers. Most applications and games just began to be optimize for Quad Core but 6 Cores is way too much. Also, using triple DDR3 channels is also way too much for a Desktop PC. Anyway, at the end, it is up to him to decide.
PS: Core i7 870 (Intel branded it as Core i7 870 while it should have been Core i5 brand) performs very close to Core i7 920 and also works on cheaper Core i5 motherboards so the truth is I don't really wanted to recommend him to get Core i7 920 or expensive high-end system like Core i7 + X58 and spending more money which could be unnecessary for him. Also, P55 motherboards like P7P55D Premium and GA-P55A-UD4P are the ones that officially support SATA 3 and USB 3.0 so it would be silly for him not to future proof himself more with SATA 3 and USB 3.0.
Recent Updated News: Please note that single PCIe x16 slot would be limit to only x8 mode on GA-P55A series motherboards especially when SATA 3 and USB 3.0 are enable. Well, that is one sad part about GA-P55A-UD4P. But for P7P55D Premium, I'm not sure. Let's hope that they will correct this negative side effect issue due to enabling SATA 3 and USB 3.0 on these P55 motherboards.