Stupid questions I know but what do the D and the E in sr20de stand for. And is that what would be in a 2001 2.0 Se w/pp. Let me know, Thanks.

All Nissan engines follow this code (atleast I think so)
For an XX00YY engine
XX - engine series designation (don't know another name for it, lol)
00 - size in L*10
YY - varies
D = dual overhead cam
E = fuel injected
T = turbo
TT = twin turbo

So the SR20DE is a 2.0L, dual overhead cam, fuel injected engine of the SR series
RB26DETT = 2.6L, dual overhead cam, fuel injected, twin turbo, RB series
etc

Yes the sr20de is what comes in the 00-01 Sentra SE, bulletproof little bastard of an engine, I love it

Yep

http://www.freshalloy.com/site/features/tech/engines/home_codes.shtml

Thanks I always wondered.