Wow. This is actually fascinating. Let me explain why:
Adwords is a registered TM of Google. Here is the info and a link to the tarr status page for adwords: (Yes I know you have adword, singular)
reg date: December 16, 2003
drawing code: (1) TYPED DRAWING
tarr status:
http://tarr.uspto.gov/servlet/tarr?regser=serial&entry=78132568
Google has litigated in the past, and my first thought was that Google either didn't know about the sale, or didn't care, or bought the mark. I couldn't believe that they didn't know... so let's look at the latest whois for adwords:
Registrant:
Google Inc.
(DOM-290716)
1600 Amphitheatre Parkway
Mountain View
CA
94043
US
Updated Date: 16-nov-2007
Creation Date: 26-jul-1999
Expiration Date: 26-jul-2008
Now let's look at Adword.com (singular, relates to your domain):
Registrant:
Lulu.com
(DOM-1714990)
860 Aviation Pkwy Ste 300 Morrisville
NC
27560 US
Updated Date: 17-nov-2007
Creation Date: 01-apr-2000
Expiration Date: 01-apr-2010
If the owner had it since 2000, then the domain predates the registered mark. Furthermore, if you look at the TM record, you see a date of first use as the year 2000. So the domain might predate the claim of first use. That would make a UDRP or suit *extremely* difficult.
The new owner is lulu.com. This will be interesting to see how it proceeds. At this point adword.com is not resolving.
Now, given all of that, the question then becomes whether Google would want to litigate or just buy a domain registered after the TM registration date. If you approach them with an offer of sale, then that alone is an issue of bad faith which can be used in court against you.
One of the legal issues here is the difference between adword and adwords, where the legal test is "Likelihood of Confusion". This one is obvious since the two terms are "confusingly similar" in the mind of a general person interested in using the phrase. Furthermore, the question arises as to whether the use of the mark Adwords on your page falls under the general category of "nominative use" of a mark, or is it infringing.
Without the infringment cloud I would say about $1000-$2000, since this term is in heavy use in our industry. With the cloud hanging over it, I would be *very* careful about this.
Good luck,
Marc