From Microsoft's website:
Regarding COMPCLN.exe, it's not really the same thing as VSP1CLN, COMPCLN clear the specified folder BUT can also remove the compatibility with Windows XP (Program, of course).
Both commands can be ran if you don't need to roll back on a previous SP and if you are almost sure that you don't need backward compatibility with XP. You can delete files manually... or better, copy somewhere and see if you have troubles.
Usually you must pay attention on WORKSTATIONS, not on servers... but anyway, I think it's better a copy instead of nothing to recover from :)
ps: ho visto che sei italiano, se hai / avrai bisogno in futuro e non sai come scriverlo in inglese, puoi scrivere in italiano che poi lo traduco io :). Ad ogni modo x adesso si capisce quello che scrivi, quindi tranquillo :)
bye