finally decided... but what to buy?

[animex]

ive been wanting to get DSLR for quite some time...

i have been using my old Canon SD200 most of the time and when my dad gave me his old Pentax Z-10 SLR, I realized how expensive it was with films and developing...

So ive decided to buy used DSLR but im quite new to DSLR and ive decided to ask few recommandations.


I will be doing lot of landscape photographing (with tripod). Since im a meteorology student, i would like to take few random pictures and perhaps doing time setting shots frame by frame to get changes in the sky and all. For this reason, i would like to have good multishot function.
I also will be taking lots of shot of storm & low light photography i guess... (lightening and all) which means I need to learn some techniques and functions to be able to get good shots but i guess i need something that can do the job well although i guess lens might be very important for this but do know, im not a pro or anything ;) so something not too high

I will be doing bit of photoshop and will start learning aperture once i get my new apple's laptop in September but ill mostly will stick to the original picture with minur editing. Also i wont be printing so much may be 10pictures every 1000 shots will be printed or less i guess.

Since it is going to be almost like a hobby for me, i dont want to get into too much of advenced stuff yet... may be once i graduate
for now, im looking at used one at $500ish range.

Please let me know what kind of body and lens i should be looking at and

oh one more thing...

I do prefer Nikon so if there is Nikon model that can get me pretty much what i am looking for, it would be great but I am open for any!

thank you guys!


===================== added

ok, i tried to narrow it down... (used)

Nikon - d80-d90 (i know it will be hard to find d90 in $500 but... for now im trying to see what model i should be looking at and what brand)
Canon - EOS 40D - 50D
Pentax - K10 - K20