Seriously: Something that *might* help not only with that problem, but would likely reduce server load (and thus, crashes in the first place) would be to run apache and mysql on different servers. IIRC, this is suggested by both apache and mysql online manuals. Question is wether to put mysql on the slower or the faster machine (assuming they're not identical).
Apache should never crash... if so, something is wrong! i'd try to install freeBSD with Apache on the slower computer, and redhat-linux with mysql4 on the faster one. Even an old PII 400 is fast enough to serve several tousand users at the same time. it should only have a lot of memory!
And.. of course.... is your internet connection bandwith limited? if so... this produces a lot of load if the server-load is near the maximum possible bw, so... keep that in mind,,,
Phil