how many MaxClients should i give?
 

i am a new lamp user. my linux os is ubuntu 7.10 and my configure is 7.5 GB of memory, 64-bit platform.
in my apache conf file
<IfModule mpm_prefork_module>
StartServers 5
MinSpareServers 5
MaxSpareServers 10
MaxClients 150
MaxRequestsPerChild 0
</IfModule>

<IfModule mpm_worker_module>
StartServers 2
MaxClients 350
MinSpareThreads 25
MaxSpareThreads 75
ThreadsPerChild 25
MaxRequestsPerChild 5000
</IfModule>

i have couple of apps in hi5,myspace and fb. these apps are getting lot of hits. so in pic hour my apache server give time out. after lot of search in google i changed the "mpm_worker_module" still i am having this issue. how can i solve this time out. should increase my ram? or increase my MaxClients in mpm_prefork_module?

It's impossible to say unless you monitor the system load to determine where the restriction is. Is it in the incoming/outgoing data bandwidth, your system memory, the number of Apache threads, or what.