SRPMs are source packages. You use them in cases where you want to compile packages yourself, but at a minimum you need a base system and compiler, plus tools, installed first. Unless you have a particular need to compile with non-standard options you won't need SRPMs, certainly not when first trying out GNU/Linux. As for server software, all the main distributions include a wide selection, Mandrake included. What sort of server operations are you planning to try out? Ignore my nick btw, I switched to Debian, guess I should have waited before registering here
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Steve