I'm editing some wedding stuff in FCP and I've noticed that when I slow a clip down to 75% or 50%, I usually get a stuttering effect. Is there a way around this? I'm coming over from Vegas where I never noticed that before. I was always told to try to slow things down by a quarter or third, but thats about it.
Any thoughts?

There are a number of things that can cause this, the first thing I would do is check and see if you need to render the timeline. To render hit (option R).
If you do a lot of slow-mo you may want to consider using the optical flow feature in Motion or even better Twixtor.

Also, if you're doing slow motion on 24p footage, it's not going to look anywhere near as smooth as slow motion on 60i footage.

I'm pretty sure all of the footage is 60i. I'm going to take a look at Twixtor as well.
Thanks!

In order to get really good-looking slo-mo in post on FCP you need to use the Optical Flow retiming which is ported over from Motion. Twixtor is much easier to use and I think has a better final output but the full motion-control suite is almost the cost of FCS2, so be prepared.

When using FCP's native speed control panel make sure that Frame Blending is selected, this should help

I'm editing some wedding stuff in FCP and I've noticed that when I slow a clip down to 75% or 50%, I usually get a stuttering effect. Is there a way around this? I'm coming over from Vegas where I never noticed that before. I was always told to try to slow things down by a quarter or third, but thats about it.
Any thoughts?

What sort of stuttering? I slow footage done all the time and never get what I would classify as a stutter. The only stutter I can imagine is if the field order was somehow reversed. What format are you shooting and editing in?

We are shooting in HDV and editing in ProRes. I'll see if I can upload some clips later.

I have the same with 50P footage which I want to slow down to 50% in a 25P project.
In Premiere Pro it would do this flawlessly, but the result in FCP is not satisfying at the moment. It is very stuttery after exporting, while the frames doesn't need to do any frame blending at all. As the imported file has double the amount of frames available.
In Adobe Premiere Pro it's called 'Interpret footage'. Is there something similar available in FCP?

in FCP you would use Cinema Tools to conform the frame rate
see this thread at the COW http://forums.creativecow.net/readpost/8/936223