scenery problem

Clean it all out and see if that helps, if not come back and we'll see how to get the sim back up to speed.

The slow and choppy could be due to a older graphics card, or other pc hardware, list your system specs for us

dell dimension 3000, p4 2.80ghz, 512mb ram, nvidia geforce 5700le

I think FEM is correct, that card is a little on the "old" side, a newer card and another 512mb ram (get to 1 gig) would make a world of difference in the performance of your computer and the sim would be smoother.
For now I would turn off, water and shadows. Turn down the sliders in settings of traffic, lower clouds to as low as possible, and keep the others at the default or lower settings.
That may give you better FPS and a nicer flight.

i can't really get a new card cuz i don't have an agp slot but when my uncle got me this card he said it would be probably the best for pci. but i can run far cry just fine, does this game require more?

alright i got rid of the airport scenery and now its working better, but are there any airport scenery that will work good for me?

This sim is very graphic intensive and demands the best, when it first came out there wasn't a computer and card to run it full out.
If you don't have a AGP slot then that's probably the best card for you.
As for as add-on scenery all you can do is download one at a time and see how they react, if they give you a big FPS hit then you'll have to look for another. Some are very FPS friendly but you have to search for them.
Someone here might know of some.
Try looking at all Avsim has.