I still have an A20m that I've owned since new. I found that I don't like using laptops very much, so I never replaced it with anything newer.
It was originally a Celeron 550MHz 64MB. It has the 15" 1024x768 screen, I guess most of them were 14".
For most of it's active life I ran it with Win2k and 256MB RAM.
In more recent years I upgraded the motherboard and CPU and also maxed out the RAM to 512MB.
Unfortunately the Celeron board doesn't support full P3s properly due to SpeedStep. It was swapped for the board from a P3 version and has a P3-900MHz CPU. The particular motherboard is an older one that wasn't supposed to support that CPU stepping, and IBM never sold it that way, but it turns out that an updated BIOS added support for it.
Nowadays I only use it for occasional special needs and so I'm probably going to put XP on it again. I had previously tried that and didn't like it, but some things don't work on Win2k so XP is necessary.
Both of these boards (both the Celeron and the current P3 board) had ATI Rage Mobility M1 graphics chips on them. Pretty useless for 3D, but at the time it seemed cool that they were capable of it on some level.
I remember that back in the day I used to be able to run 3DMark2000 successfully. Later on, I discovered I couldn't run 3DMark anymore. I don't remember the exact error but I was convinced I needed an older driver - but IBM had apparently removed them from their site.
I have a couple batteries. One of them is a 4hr battery that lasts around an hour, the other is my original 2hr battery which lasts maybe 15mins. The fact that this laptop still has any battery life at all is one advantage it has over my P1 laptops. Otherwise I consider the P1 machines more utilitarian due to their heavier construction.
Now that it's only useful to me for portable applications, I don't feel like the Thinkpad A20m (a "desktop replacement" model) is very well suited. If I ever saw an X-series cheap, I might be tempted to get one.