What kind of effects are you speaking of? If you're talking simple effects like transitions and filters then just about any of the editing softwares offer some form or another. Obviously the higher end progs offer more. I cut on Vegas Video 5 and it has more than enough.
Now if your talking special effects like laser blasts, muzzle flashes etc. Bar none, hands down the best one for the money is AlamDV which you can find at
http://www.fxhome.com For the money it's awsome. What's best about it is the website, there are hundreds of plugins that users created. explosions, light sabers, characters, etc. I'm pretty sure that you can dl a trial and the AlamDV3 will be out soon which is supposed to be more powerful. I've used it for about a year now and it's awsome. Hope this helps