Don't think there are any. If you're renting from a game hosting service, put more weight on what level of access and control and quality of their tech support. If you are renting or setting up you own server, weigh your decision on how strong your Linux versus Windows skills are.
I think I have a problem with windows. I have server with 512 Ram and cpu 900 MHz sometimes crash my server and not from any additional pk3 or mod. crash the server every time a different map, and not always. This happens always when loading the next map
It may be maxing out the CPU - Spearhead was a big jump in CPU load over Allied Assault. Are you running anything else - IIS, ftp, voice chat server, etc? If so, your CPU may simply be pegged.
Since map loads tend to involve a lot of disk I/O and probably a temporary crunch on memory, check to see if your hard drive has about 20% free space (minimum 10%). Also run defrag if it has been around a while and had a lot of files added and removed over time.
Back on the background programs issue, I used to periodically wipe a Windows system clean and reinstall (and patch) Windows. The performance improvement can be amazing if you do like most people and try out new programs a lot. Uninstall routines often miss stuff that hangs around and sucks down resources or just clutters things up.
You can try a linux OS - but look for a stripped down old school Linux option - not one of the latest "look, I got a big fat GUI just like Windows" distribution. Your hardware is not horribly powerful, so you need to minimize what is running.
Bad news is, old school Linux has a steeper learning curve than one with all the GUI based stuff.
If you don't have some Linux experience under your belt, try cleaning up your Windows box first. If you have a handle on what you are doing, run msconfig from the Run menu/command prompt. Use it to catch stuff that is autostarting in the background and stop them from spinning up. Just don't turn off stuff you need or you will have to visit safe mode to get things going again.
How should I get the minimum cpu and Ram; I have xp if I put win 98 will be better; and What are the minimum hardware requirements to spearhead server 10 people; I think of to buy a new hardware and I want your experience