Here is my impression of both these cars that I don't own
The 00 SER is one of my friends. This car handles very well. Actually I loved everything about the car except one thing, the design on the seats! It looks like they stole them out of a Hyundai! Anyways, the brakes were superb. It shifted nice but it had a stock 1.8 feel for it when shifting. It made most of its power in the upper range around 4k and up. It was pretty quick and way better throttle response than the older 2.0's. All in all a very sporty car.
Now the SPEC V is a whole new animal which I love. First let me jump ahead to what really sold the car for me (even though this one was my friends too!). The six speed gearbox. That SOB was geared so close I almost crapped my pants. It was the best gearbox I have every driven in a small car or just about any car for the matter except for some higher end cars, Audi, BMW, Porsche. Its close ratio used every part of torque when rowing through the gears. Now back to the rest of the car. The engine had just about everything the 2.0 didn't. It has alot of torque and it revs pretty high for its long stroke. The Rockford Fosgate stereo was amazing for Sentra. The gauges where very easy to read and looked really cool. I liked everything about the car actually except one thing, the grill. It looks out of place. I don't know why but it does. As for the interior, at least Nissan got better looking seats in it. This car was a blast to drive. If Nissan didn't put the 6 speed gearbox in that car, I don't think it would sell as many as it did. Just thought I would throw my opinion in. I think if everything goes well I may buy one next year or the year after(07).
James