Nice to meet you too!
I tried the trial (well.. the whole point of a trial is to try..!) for ZenDesk but I honestly thought it was too advanced, not that I didn't know how to work it, but because the features were too many for what I need. I haven't tried Assistly but for a solo VA it could be perfect (I'm not a solo VA, I run a small VA company) - you could sign up for a trial.. I think it's either 15 days or 30 days free trial without having to enter any credit card details. Last night I came across a site called Projify which sounds great, I've got a lot on today so not had the chance to sign up but from what I can see it has a shared calendar, ticket/helpdesk system, shared files, etc. Unlike it's competitors it charges per project and not per user. It's 5 Euros per project and you can easily add on that small charge on your invoice to the client. Worth checking out.