apart from paying through the nose to someone like ATI for this, the best source is the Flight International World Airliner Census which they publish once a year in the weekly magazine - coincidentally, the last one was 24th August 2004, so the new one should be out soon, may be worth e mailing the magazine about what date?
The numbers you seek based on last year's figures:
A320 family:
318 - 6 total (1 operator)
319 - 202 (24)
320 - 491 (62)
321 - 179 (33)
B737:
-200: 49 (11)
-300: 268 (54)
-400: 188 (36)
-500: 155 (25)
-600: 37 (3)
-700: 110 (17)
-800: 297 (31)
-900: 5 (1)
Caveats: the numbers are a year old and don't include orders, the operator numbers were a very quick count by me, and "Europe" is a very loose term including Russia.