(more info / perspective, FWIW)
A 35 mm lens on a crop sensor (DX) is roughly equivalent to using a 'standard' 50 mm lens on either an full frame sensor (FX) or on a 35 mm film camera. (The D5000 has a crop (DX) sensor, right?) I.e. and IMO, it's generally a more useful lens day-to-day.
The 35 mm is a 'G' type lens and requires a body that controls the aperture with a command wheel.
The 35 mm is a DX lens and will fully image only DX sensors.
The 50 mm is a not a DX lens and will fully image DX, FX and 35 mm film.
For the implicit question of "Which of these two should you get?", unless you plan on getting an FX body or a film body, or plan on doing a bunch of portraits within a year or so, get the 35 mm, f/1.8 (even though it costs more). If I had to choose only one prime lens to use with a crop sensor, I'd choose a 35 mm.
BTW, did you see the stitched images I put in the Photo Tag thread? Two of them were taken with my 35 mm lens. Here are those and a few more:
http://homepage.mac.com/mosquito/2010-BARF-Photo-Tag-Big/large-7.html
http://homepage.mac.com/mosquito/2010-BARF-Photo-Tag-Big/large-8.html
http://homepage.mac.com/mosquito/2010-BARF-Photo-Tag-Big/large-1.html
http://homepage.mac.com/mosquito/2010-BARF-Photo-Tag/large-31.html
http://homepage.mac.com/mosquito/2010-BARF-Photo-Tag/large-32.html
A 35 mm lens on a crop sensor (DX) is roughly equivalent to using a 'standard' 50 mm lens on either an full frame sensor (FX) or on a 35 mm film camera. (The D5000 has a crop (DX) sensor, right?) I.e. and IMO, it's generally a more useful lens day-to-day.
The 35 mm is a 'G' type lens and requires a body that controls the aperture with a command wheel.
The 35 mm is a DX lens and will fully image only DX sensors.
The 50 mm is a not a DX lens and will fully image DX, FX and 35 mm film.
For the implicit question of "Which of these two should you get?", unless you plan on getting an FX body or a film body, or plan on doing a bunch of portraits within a year or so, get the 35 mm, f/1.8 (even though it costs more). If I had to choose only one prime lens to use with a crop sensor, I'd choose a 35 mm.
BTW, did you see the stitched images I put in the Photo Tag thread? Two of them were taken with my 35 mm lens. Here are those and a few more:
http://homepage.mac.com/mosquito/2010-BARF-Photo-Tag-Big/large-7.html
http://homepage.mac.com/mosquito/2010-BARF-Photo-Tag-Big/large-8.html
http://homepage.mac.com/mosquito/2010-BARF-Photo-Tag-Big/large-1.html
http://homepage.mac.com/mosquito/2010-BARF-Photo-Tag/large-31.html
http://homepage.mac.com/mosquito/2010-BARF-Photo-Tag/large-32.html


I have it though.