Yes, it's that simple. X24 requires PC133 memory modules.
Thank you, that's a pain, I've got a few spare PC-100s, the only PC-133 I have that can be switched with PC-100 are in a Thinkpad web server, I daren't destroy the uptime of that so... back to ebay it is for some PC-133, at least that way I can make sure I get a 512MB chip for it
Edit: Thank you for adding the additional information, that will no doubt come in handy as I own a few laptops from that era (and intend to own more over time)
Also it may be worth noting that the T20 can sometimes work with PC-133 as long as it is in slot 2 and their is a PC-100 chip in slot 1.
4xT20, T23, T60 (Pinkpad for my daughters), X22 (password locked), X24, 2xR40e, A20m, 600e, 701chttp://thevdm.com