<p>I am currently looking at a distributed cache solution. </p>

<p>If money was not an issue, which would you recommend?</p>

<ul>
<li><a href="http://www.scaleoutsoftware.com/" rel="nofollow noreferrer">www.scaleoutsoftware.com</a></li>
<li><a href="http://www.alachisoft.com/ncache/" rel="nofollow noreferrer">ncache</a></li>
<li><a href="http://sourceforge.net/projects/memcacheddotnet/" rel="nofollow noreferrer">memcacheddotnet</a></li>
<li><a href="http://www.microsoft.com/downloads/details.aspx?FamilyId=B24C3708-EEFF-4055-A867-19B5851E7CD2&amp;displaylang=en" rel="nofollow noreferrer">MS Velocity</a></li>
</ul>

Out of your selection I've only ever attempted to use memcached, and even then it wasn't the C#/.NET libraries.
However memcached technology is fairly well proven, just
look at the sites that use it
:
...The system is used by several very large, well-known sites including
YouTube
,
LiveJournal
,
Slashdot
,
Wikipedia
,
SourceForge
, ShowClix, GameFAQs,
Facebook
,
Digg
,
Twitter
, Fotolog, BoardGameGeek, NYTimes.com, deviantART, Jamendo, Kayak, VxV,
ThePirateBay
and Netlog.
I don't really see a reason to look at the other solution's.
Good Luck,
Brian G
.