Should I remove these Norton files?

I have a HP desk top with Vista Home and Vista Service pack 1

 

I use NAV2008

 

When I got the computer in July 2007 it came with a trial of NIS 2007. After the trial expired I purchased NAV2007. Whne that expired I purchased NAV2008. When that expired, I continued on the subscription for NAV2008

 

My question, Ihave noticed in various folders older NAV items examples:

 

C:\ProgramFiles\CommonFiles\SymantecShared\

EENGINE(145)

EENGINE(311)  and about 10 in between all dated around 10/2007

 except for a current EENGINE without a number dated 5/22/09

 

C:\ProgramFiles\CommonFiles\SymantecShared\VirusDefs  that is dated 9/15/07 and is empty

 

when I do show hidden folders

 

C:\ProgramData\Symantec\Defs\VirusDefs\

 I have folders from 2007 some empty some containing items

 

(in C:\ProgramData\Symantec\Defs\VirusDefs\  I do have recent folders from today 5/22/09 and 5/21/09)

 

So my question is, should I delete these older folders? Or just leave them alone? I'm very computer stupid so the less I do, the beter to keep me from messing things up.