If you can swing it, I would definitely go with the 330. My wife and I had been considering a 3-series for about a year, and we were looking at Factory Executive E46 cars with about 16,000 miles on them. We figured if we could get a good one for under 30 grand, it would be doable.
Well, after driving lots of 325s, we found a 2003 330ci, 5-speed CPO car with 38,000 miles on it, at the right price, and we bought it last weekend.
Here's what we found - all the 325s felt good and solid, but we came away just feeling that the power was a little lacking. I may be lambasted for this, but in our eyes, the 325 is sort of BMWs "secretary's car" - you know, lots of bells and whistles, really comfortable, handles well, but not a whole lot of power. The 330 has that "missing factor" in the equation that brings a smile to our faces when we drive it - instant throttle response.
Now, you can always do a lot of tweaks and mods to the 325 to give it more power, but why bother if you can get a 330 which had it from the factory.
Cheers,
Paul Kile
330
Newbie and Loving It!