All of the below is off the top of my head, and applies to US models only. Check out the BMW 3-series forum at edmunds.com for really detailed info, including what price you should shoot for ($1400 over invoice last I checked).
The 330 comes standard with some equipment that the 325 does not, such as the sport suspension.
The 330 is available with 18-inch wheels, the 325 is not.
I've heard the 330 gets better gas mileage, although I don't know for sure. The 325 engine is simply a destroked/bored version of the 330, so maybe it's possible.
The 330 sport package looks more like the M3 than the 325 sport package.
The 330 uses a ZF 5-speed manual whereas the 325 uses a Getrag unit.
There is no "is" trim line anymore. That stopped with the E36 (1998 was the last year) model. The available trim lines are i (rear wheel drive) xi (all wheel drive) Ci (coupe, rear wheel drive) CiC (Convertible, rear wheel drive), and of course M
The G35 is as good if not better car than the 330i, and it's cheaper. Period. Personally, I don't like the styling. I haven't seen the interior close up to make a judgment on that. If you like the styling of the G35, I doubt you'll be disappointed by anything else. But for the love of all that is good and holy, wait for the manual version.
Edit: BTW, there was a subtle styling change in 2002. Best I can describe it is that the headlights look more teardrop shaped. Frankly, I think 2001 was the best looking model year thus far. Think about buying a CPO BMW either this year or the next. There'll be a bunch of them coming off lease, and you get a 7 year warranty. Keep in mind that the sport suspension was not standard on the 330 before 2002, so if that's important to you, make sure it has it. Also, don't be afraid to buy your BMW at a dealership a good distance away from you if you can get a good deal. You can still have it serviced at your local BMW dealer. Also consider doing European Delivery. More info is available at BMWs website, but basically you get a hefty enough discount to pay for a trip to Germany to pick up your BMW. Good deal.
