1) When you say you "changed the capture settings", do you mean you changed the encoding settings?
2) When you say "bad quality" are you able to qualify this? Is it fuzzy/pixelated/stuttery/washed out/grainy/has horizontal lines etc etc. If you can, post a screen shot.
3) Have you tried outputting as progressive (de-interlaced) as Millsy suggested?
www.100fps.com
4) The capture process should be lossless. Have you defragmented your harddrive?