Best Linux choice for proxy/firewall?

I would go with Redhat 7.2
Squid as the proxy server
IP chains as firewall
You could run an ftp server on the same box - I would tend to seperate this from the firewall

My choice is SNF.
Mandrake Single Network Firewall(SNF) is
a stripped linux distro with all unnecessary junk
removed. It has a webinterfac towards the LAN and is easy to configure. Installation is also easy. All u need 2 do is download an ISO image, make a cd from it and boot your firewall-to-be with the cd.
ISO-files can be found at:
ftp://carroll.cac.psu.edu/pub/linux/distributions/mandrake-iso/i586
ftp://ftp.cse.buffalo.edu/pub/Linux/mandrake-iso/i586
ftp://ftp.stealth.net/pub/mirrors/ftp.mandrake.com/Mandrake-iso/i586
ftp://ftp.wtfo.com/pub/linux/mandrake-iso/i586
ftp://jungle.metalab.unc.edu/pub/Linux/distributions/mandrake/Mandrake-iso/i586 .
Be sure to remove any spaces within the links.
More info, documentation and links to reviews can be found at http://www.linux-mandrake.com/

IMHO it is safer to run FTP at a separate computer.

Regards // Tom

Mandrake SNF
Mandrakesoft has provides a high quality product, and maintains excellent hardware support. They also seem to keep on top of errata and notifying of updates.