My husband and I have started our own business less than 6 months ago, as an aside to our day jobs. We expected to get some contracts and be relatively busy, but the response has been unbelievable, with word-of-mouth causing our name to spread like wildfire.

However, I still feel that I haven't got the necessary tools to manage the business.

My current system goes as follows:
* A couple of excel worksheets tracking all invoices to be sent, to be paid or already paid
* Basecamp free account for my personal to-do list (call x, review contract from x, etc)
* Google Calendar with multiple calendars to allocate time to each project, remind us when an invoice is overdue, assigning meeting dates, etc
* Exchanging text files back and forth with project specs
* Address book and a messy email archive for contact details of each clients
* Invoices created in Pages and sent as pdf

It certainly isn't centralised or easy to maintain, and as I'd rather spend time on really dealing with the clients, rather than fudging spreadsheets together, I thought I'd ask the wise people of 43folders to suggest some applications which could help us out. We considered writing our own, but I would imagine something already exists.

My wishlist goes like this:
* Calendar entry relates to a page/doc with specs/message and to contact details, and maybe even work history of the client
* Web-based (as a total ideal: can be installed on our own server rather than hosted by 3rd party)
* A way to track invoices and get an email reminder if it becomes overdue
* Easy to-do lists
* No need for complicated charts, as long as there's some basic time management/allocation tool (even an integrated calendar is good enough)
* We're both on Mac, so something that's Mac-friendly but can be used on Windows as well

I've tried a few systems like Zoho, Sidejobtrack and a few bigger systems which are meant for larger businesses, but I just haven't found the right thing yet. I quite like the Basecamp simplicity but my husband doesn't like it, and wants something that offers a better calendar-style snapshot of the month ahead. I'm also willing to pay a reasonable price if the app really fits the bill.

Would anyone have recommendations on the best apps for this type of work? Has anyone tweaked any of the systems above to meet their needs?