Go for it. You will love the week being among felllow divers. I am a solo (not single) female 53 yr old with only one year certified and only 57 dives, and did two trips last year. Each time I found both the crew and my dive mates friendly and open. I have kept in touch via email and phone with several from my second trip. We are planning another trip together for 2008. And one couple I met will be traveling with us on a land trip this May, then visiting us (my husband and I) for a few days next Sept.
I would not suggest bringing a non-diving spouse (like my husband) on a liveaboard trip. When they say "eat, sleep, dive" they left out "and talk about diving" which is what the conversations are about all the time you aren't eating, sleeping or diving.
Go it alone, but you won't be alone for long after the first hour on board.
mjarens