The little reading I've done says "The RaQ2 can handle over 250K emails and 10M page views per day." This is sales stuff, and probably the top of the line at 256MB ram and 16.8 gig drive and dual ethernet. Even the bottom of the line with 16MB ram, 4.3 gig disk and single ethernet is probably overkill for your needs and costs around $1150 with Apache/Linux and plenty of bells and whistles. It's surprisingly economical.
The Cobalt [cobalt.com] site doesn't provide much detail on the Raq2 but I found some info at RaqNet [raq.net].
I'm looking at just leasing a Raq3i. I'm not fond of colocation - I've been burnt once for several grand due to hardware failures and that alpha is now an expensive foot warmer under the desk here. (although I will say, my toes are staying toasty on these cool fall nights).
I am trying to figure out how much ram it will take. I don't know if 64meg would be enough for our usage. The one knock I've always heard about Raq's is they are slow at running of cgi's due to the slow cgi wrapper used on all cgi calls.