A friend of mine has the Xcruise w/ the 420w but only has A64-2800 & 6600GT and it does work, but for yours you will probably want more (like dual rail & sli). You can get them w/o any power supply from newegg.
The XG Dragon has a 500W w/ active PFC and SLI approved, I tried to find the specs but it does not list them directly on xgbox.com - I wonder if they are using their "vortec" power supply line. If so those models do not look so bad. here
is the manufacturer link..