Hello there, a couple of specialist memory sites; mrmemory.co.uk and offtek.co.uk are offering memory modules for a Thinkpad T23 type 1872-xxx that is apparently capable of taking up to 2Gb. Now I've checked on the IBM "307" site and there is no recognised type 1872 there (only the usual 2647 and 2648 flavours) so I'm not sure what is going on there?
Either these sites have both got some kind of database error and the type 1872 belongs to another Thinkpad family, or there is some kind of T23 forgotten *****Expletives removed by Moderator***** child that IBM have disowned... I suspect the former, although nothing would surprise me!
On further inspection the T43 has a type 1872 so mystery solved. I guess beware of those memory companies and always check with the IBM site to see what your older thinkpad is capable of!