Thinkpad 600X and RH7.2

Dear list,

I have installed RedHat 7.2 on a Thinkpad 600X. I am wondering why my 
machine crashes sporadically.

Video: Neomagic 256 (for laptop/notebook)
Processor: P3, 500mhz (120mhz when booting up with the battery)
RAM: 192MB (up from 64 out of the box)
Kernal: 2.4.7-10
KDE 2.2.1
XFree86 4.1.0
emacs: 20

When I first put RH 7.2 on the machine last week (when it still had only 
64MB of ram), KDE was very unstable; clicking on Start, then another menu, 
would hang up the machine (mouse movement, but no other activity). (I think 
Gnome was also unstable, but I only tried it once and then went over to 
KDE.) (This is a dual boot system with 98 on as well, and 98 seems 
perfectly stable.) I did a few things, the first two suggested by various 
experiences people have posted:

(1) add a line

	Option		"XaaNoScanlineCPUToScreenColorExpandFill"

to XF86Config

(2) set the BIOS internal pointing device from AutoEnable to Enable

(3) installed 128mb ram

RAM seemed like the most plausible explanation, since (a) RedHat says you 
want 96mb minimum, and (b) the machine was crashing in various different 
emacs tasks (pulling down a menu; running LaTeX on a not-very-big file).

After adding ram it got a lot more stable, but it still crashes; the last 
time after I installed AucTeX for emacs and was pulling down menus fairly 
rapidly with 5 emacs frames open and a couple of shell windows.

Is this just a ram problem? Why is RH 7.2 so unstable with 192mb? How much 
ram do I need?

Or is it something else? emacs? the version of XFree86?

Thanks!

Tony Dardis