windows 2000 server – virus defenitions

i have windows 2000 server( domain)in which Symantec system center is installed

when ever i found and update in symantec site i updates it
My problem is that
in C:\Program Files\Common files\Symantec Shared\VirusDefs, there are a lot of folders named
20020821.007
20021127.005
20030609.006

etc, etc…

i think these are the virus defenitions i update
but since 21/2 years this procedure is happening and teh free space in my c Drive is coming down

i want to know that , can i delete the old virus defenition folders from this location

will it affect my symantec system center to detect any sort of virus

pls help me
some how i need to increase free space in C drive and only this folders are occupieng 55% c drive

Thanks in advance