I'm interested in purchasing the entire series either on VHS or DVD
(preferrably DVD).  Can you tell me if it's available or if there are
any plans for distributing the series?  Thank you for your help.

I am posting this as a comment, rather than an answer, because I do
not know whether this option is satisfactory.

"The Waltons" is not yet available on DVD, but Columbia House Video is
offering "The Waltons" on VHS. This is a "club" where they send you
one tape a month. I believe each tape contains two one-hour episodes:

http://go.columbiahouse.com/cache/home.do?club=4&dk=ABQ&cache=true&v=193&mode=QJR&group=PAYMENT

Membership details for Columbia House:

http://go.columbiahouse.com/cache/membership_details.do?type=membership_details&name=skip&club=4&dk=ABQ&group=PAYMENT&mode=QJR&language=en&&cache=true&v=193

There are many episodes for sale on eBay:

http://search.ebay.com/search/search.dll?MfcISAPICommand=GetResult&query=waltons+vhs&cgiurl=http%3A%2F%2Fcgi.ebay.com%2Fws%2F&ht=1&from=R10&currdisp=2&itemtimedisp=1&st=2&SortProperty=MetaEndSort&BasicSearch=

cayne72 - 

They start airing again on the Hallmark cable channel Jan 13 -

http://www.hallmarkchannel.com/jsp/hallmarkchannel/ds_Framework.jsp?FUELAP_SITEDBID=SITE%5F%2D66&FUELAP_OP=FUELOP_NewScreen&SETCONTENT=US%5FPROGRAM%5F85212&BODY=ds%5FProgram%2Ejsp&

Have fun recording!

thanks,
ragingacademic