Client Management Software

Greetings all,
I have purchased a system in the past to manage my website clients. However, the system is not very functional and is not user friendly. http://www.forperfect.com/


I register domains for clients, host those clients and also bill those clients for web development services.
I want a system that I can add new products, where recurring or one time charges, and then have those invoices emailed to the client as PDF attachments.

What do you web developers use to manage your clients and manage the recurring charges like hosting and domain registration services? What do you use to bill your clients for web services.

I am looking for an online solution only. One that a client can login via a web panel on my own site and then view their invoices.
Let me know guys. Thanks.