Glenn did you typo?
You want to purchase a 2005, not 2003, right?
With Symantec's anti-virus and other products (parts of System Works) the program starts its 1-year subscription from the date of registration. So if you're talking about the 2005 I concur with Chuck. Yes.
I usually purchase the newer Symantec/Norton upgrade instead of just resubscribing for updates the older version.
As more information, in fact, I've been burned by this. Last year I purchased the newer Antivirus package (2004) to replace my 2003 one which had about a month left in the subscription but was warning me it was about to expire. I loaded the new version that I had downloaded from the Symantec upgrade site. Then when I reg'd of course I got 1 year of subscription. But not 1 year plus the month remaining on my old package. Boy was I ticked off because I thought they'd treat their loyal customers better than that.
I learned my lesson and this year I upgraded to NAV 2005 after the last subscription day had passed on the 2004 version.
BTW, you might want to consider the Premier System Works version, because it includes the program named "Ghost". This is a lifesaver program that lets you restore your computer's drive to a previously saved state in about 15 minutes. (Takes far, far longer to save the backup in the first place, and the user interface is DOS and geeky, but if you can stomach that it'll save yer butt faster than anything else when everything goes haywire.)
[edit -- oops, we cross-posted. Sorry. 2 issues involved with the old one. 1) Is Symantec still offering subscriptions to 2003? 2) You may need to clean the data referring to the first 2003 install from your registry tree. (Ick!) After kicking yourself for saving the money but wasting your time you may find it easier to buy the newer version.]