Integration Manager and Scribe win the prize for the easiest to use integration tools. If you're not a developer and want to create/maintain the integration yourself, you should probably stick with one of these. Do remember that on version 10.0 of Microsoft Dynamics GP that Integration Manager comes with several new "eConnect" integration types, which will make integration manager much faster. I don't remember off hand if lockbox or cash receipts are available as one of them. Check with your VAR.
Outside of these tools, if you are a developer or you have a developer on staff and are willing to setup a more complex integration, SQL Server integration services (SSIS) works very, very well, and is a much more robust integration design interface for hooking up to your souce file (like Excel). For going into GP, I would probably recommend going direct to the eConnect stored procedures, which are installed by default on version 10.0. A little daunting perhaps, but it's the method we employ most frequently.
Take care,
Ron
Ron Draganowski
Senior Solution Developer
Olsen Thielen Technologies, Inc.
rdrag@ottechnologies.com
www.ottechnologies.com
Find me on LinkedIn: http://www.linkedin.com/in/rondraganowski