The best hardware for server under linux or window server 2003

[assy23]

What is the best hardware server under linux ,unbuto or red hat
what is the best hardware server under windows 2003
the minimum and maximum memory
kingston 4gb 800mhz is enough for server
cpu intel quad is good enough ?
Or amd opteron cpu are better for this

[forumdz]

and what is the maximum number of connected peers at a time ?

thanks

Djoss.