Using old hardware to make a torrent box.

I build a small wiring closet in an empty closet in my house with my modem and router. I plan to also put a small machine to download torrents for me to.

The specs will most likely be crap I have in my basement:
Pentium III ~450Mhz and matching ASUS motherboard. Probably very little RAM, assume a single stick of 128mb. Generic video card, not even sure if it will be AGP. I'm probably going to have to buy a small harddrive around 20-40Gb. The machine won't have much cooling since it'll need to be quiet.

The features I'd like are webserver and torrent client+web interface. I want the most lightweight OS and software.

What are you suggestings?

Use Gentoo, lighttpd, and rTorrent.

rTorrent has some kind of interface where you can drop torrents in a directory and it will pick them up, write a quick Perl interface for uploading, or use Samba. You could even put the torrents on your local computer and rTorrent will pick them up when you put them there, I guess.

If you need more web interface thingies... rTorrent is open source ;) And it might have something built in already, I don't know.

Apache is a memory hog and not made for single-user use.

Gentoo won't take very long to compile on that beast of a machine.