It had too many prerequisites to get it to run, which is a shame because it looks good.

Agreed. If I remember right, I had to compile a new PHP version to get it to run, as the one in my distro didn't quite have all the bits it wanted. The install I'm running hasn't been upgraded in a long time due to this. Squirrelmail is also running on my system as well, as one of the other miniinfo.net users prefers it.

If you plan on archiving a ton of e-mail and later searching it, I do recommend investing the time into IMP though. It seems to be much less resource intensive then Squirrelmail for searching, and much quicker. I have all my e-mail back to 98 archived in it.

One thing that is nice about Horde is the API. I'm slowly finishing a web based procmail editor that will simply plug into Horde. I'm also looking at the other Horde projects to help justify my time investment in getting it installed

I'm going to be reloading my Linux server here in the next few months, I'll let you know if anything has improved on the installation front.