mwz26 - welcome to the club, you will truley love your t45's and center. As far as the rears go, I would wait and save money for some Image B's, ideally B15's to match your towers. Anything for surrounds will work use something cheap to get you by, but sonically your best sticking with Images. They will blend in much better and not sound like a seperate entity. I suggest you pop in Dark Side of the Moon, preferably in SACD, sit back, close your eyes and enjoy.
Has far as powering my Images I am currently using my NAD reciever and its more than enough. I wish I would of went with the NAD T163 preamp and ran NAD's 7 channel amp, biamping the towers. I am looking at getting 4 Integra 2 channel amps from a buddy of mine, 1 per tower - biamped, half of one for center, and the fourth for rears. Your towers, or fronts, are really the only speakers that should need more power than a reciever can give them, and thats only for music play back. Movies and such you shouldnt really need anything more powerful. From what I have experienced, NAD power is the way to go with PSBs, maybe because they are both from Canada, I dont know, but its the best combination I have tried, I had an Integra reciever, Onkyo, and the NAD was leaps and bounds above in sound quality.