Hi,
Looking at top from shell can help.
Also, you may want to type in ;
watch pstree
from shell.
That will show you all running processes as well as how many instances each is running.
If your running a high load and look at that, it will show you if there are a ton of httpd,(web pages) exim, or other email programs, and let you know if it is a particular thing that is driving up the load.
You can have a busy site, and not kill the server, but from the sounds of it without seeing top and pstree, it is hard to say if you need a better,(stronger) server.
It could well be a spammer hitting your server and many times you can see that simply by looking at the pstree, and seeing a ton of email servers running.
If it is simply web pages, then look into which of the busy sites are getting hit the hardest, and perhaps offer two or three of them to share a dedicated, so they can afford it better.
If that's not an option, then look into a pent 3.3, and maybe double your ram.
Also, with real busy sites, you will have hard drive failures more often. Look into a raid mirror drive system to say up when the main disk crashes. Make sure to do daily, weekly, and monthly backups also. Some times, the currupt data from the bad hard drive will move onto the mirror drive. Then you will need the backups.
Tim L