The more recent higher-end Canon SLRs perform superbly at high ISOs and up until the new D3 have had much cleaner images than Nikon and all other 35mm slr manufacturers. My current digital camera is a Canon 1d mk3 and I've found ISO 1600/3200 to be comparable to ISO 400 film.
As with yourself, I was and still am a medium format film user (Hasselblad 503CW) but found the learning curve quite easy, but this is slightly decided by which brand of camera you use. I really don't like the handling of Nikons and find Canon much more intuitive (personal preference, nothing wrong with Nikon though).
Really you should try to visit a shop if possible and handle the different cameras. Well within your budget is a 5D with either 24-70 f2.8 lens or better still the 24-105mm f4 IS (you lose 1 stop but much more versatile and with IS). Better image quality still is the 1d mk3 but also more cost, weight, bulk etc.
As with Anders_HK, I am also unconvinced digital beats film but I would say the 5D/1D come close to colour neg quality, but for certain types of photography well off the quality of say Velvia 50. Good luck with your choice.