First, MSN does rely on metas to some extent by their own admission. However, they look at your description tag and seem to ignore your keyword tags. You desc tag is compared to your content and ranked accordingly. Also important to MSN, like other engines, is site's pointing/linking to yours.
Also, a page need not be frequently updated to be liked by search engine, IMO. However, if you're arrogant enough to put in expires-after or revisit tags of short duration without updating, I think that
could do damage.
I launched
Tax Help Site in the fall. To be honest, it was with the sole, hopeful intention that some CPA or lawyer would want to buy it. The pages haven't been updated for months, but ranks at the top (in MSN, Yahoo, AltaVista, others sans Google) for the intended keywords still today. Many of my pages on
FreshDames also rank well out of millions of results without frequent updates. "female celebrity sites" has 1.1 MILLION results in MSN; I'm consistently top 5, as just one example.
Finally, if my opinion is worth anything to anyone but me ... other key factors for MSN:
Title
Content
URL structure (short, relevant and static)
File Size (fast loading is better!!)
Links (internal and external / sitemap is a big help)
Good luck and Happy Ranking!