[ale] Open source accounting/inventory/pos?

[jb at sourceillustrated.com (John Wells)]

Guys,

I have a friend who's looking to start a retail store. He's come to me
for help in finding the right software, but my knowledge in this area
is about 5 years old.

What would you recommend in terms of open source business information
systems? He's looking for accounting, integrated with inventory,
integrated with a POS system.

It doesn't necessarily have to be open source...he has some
funds...but even with an off-the-shelf system he pays for he'd like it
to be very flexible (and I believe open source brings this to the
table).

I appreciate any help you can offer.

Thanks!
John