I just bought some presets and haven't figured out how to install them into LR - I have a PC if that makes a difference?
Can you help a newbie out? Thanks.

put the presets in c:\documents & settings\your username\application data\adobe\lightroom\develop presets

application data is a hidden folder so you need to be able to see hidden folders or start lightroom 1.1 and click help/go to lightroom presets folder.

What Matt said.

username? app. data? adobe? Where should I be looking for this? I'm sure it's all right under my nose, right?

Anyone?

Ok, I just was trying to figure this out on a pc too. So, I tried to make some understanding of what Matt said, but I couldn't. But, I figured it out. Here is what I did.
Right click on the start button.
Select Explore
Double Click on the folder that says aplication data
Double Click on Adobe
Double Click on Lightroom
Double Click on Develop Presets
Drag or Copy your presets into the folder
Restart Lightroom and they will be there!

Double click my computer
Double click C:\
Double click documents & settings
Double click your logged in user name - most people have this setup as their own name.
In the address bar type application data and press enter
Double click adobe
Double click lightroom
Double click develop presets

Put them in there & restart Lightroom.

Ohhhh! Got it! Thanks Neal, Matt and Kari...and Matt thanks again for the 10 dollar presets! Gotta go play now...

Hey guys,

How about for a Mac?
I can't find any PRESET folder in my Lightroom...
When I click Lightroom in the Applications folder, only the icon of the application appears...

Thanks,
Dennis

It doesn't seem to matter where they are on a Mac.

Just right click/ctrl click in the "Preset" box in LR and "import..." and show it where they are. I just made a random folder for mine