I have a PNY 16g class 4 SD card that I use in my D90.
Shooting JPG Fine - 2.1k (2100) +
Shooting JPG Fine and RAW - 711
I would guess your going to get some where around 2000 on your card shooting JPG Fine only.
JPEG file sizes vary based upon camera model and default settings, as well as user-selected resolution and compression mode settings.
Having a few smaller memory cards is better than having one huge one in case you lose it or it gets broken.
Don't put all your eggs in one basket.
Hope this helps