RandomGoon... As a suggestion for that tired old P133 BTW how much memory is in it? A good guess would tell me 32MB? Anyway maybe you'd want to consider Slackware or if you already have Windoze on it then get Zipslack which will run off a FAT file system and for a GUI run Fluxbox or Blackbox or IceWM. Just read a post at LinuxQuestions.org where someone saw a P100 system running Vector Linux with IceWM using the Opera web browser and apparently it ran pretty quick.
As for Mandrake I ran an install of 10 Beta2 version on a Celeron 2.4G system with 384MB and had it running for a few days and seemed to run fine just doing the basic stuff web browsing, wordprocessing ..that kind of stuff, ran Knoppix on it too and Gnoppix and finally Slackware and they all ran just fine except for Gnoppix which ran fine but seemed to be a bit of a memory glutton.
My main system is running Mandrake 9.1 (Duron 1200, 256MB RAM) and it's run flawlessly.
My uptime is 24 days 21:38 without a reboot.