Apache Open For Business is a top level Apache Foundation project that provides a framework for building ERP systems. It is built on top of a lot of other Apache projects - application servers, database engines etc - that are mostly written in Java.
It is not an out of the box solution. There is only one company listed as providing support in New Zealand, but I am pretty sure I know of others.
Odoo was released as Tiny ERP in 2005, and re-branded as OpenERP in 2009 and as Odoo in 2014. Odoo is a full featured system that tries to do everything - it includes a website builder, fleet manager, event manager, kitchen sink, and so on.
The demo looks really good - they will let you set up and play with an instance for fifteen days, so there is the opportunity to try it out with little initial outlay of time and effort. Configuring such a large system is daunting, though.
Most Linux distributions come with a utility to make bootable USB sticks from an .iso image. In Kubuntu, it is the Live USB Creator (usb-creator-kde). Unfortunately, it is not as reliable as it could be - while trying to make a Trinity Rescue USB, it would not load the iso file. Unetbootin is a reliable alternative to the default KDE utility.
NOTE: None of the USB disk maker utilities seem to be 100% reliable - so best to check the disk works before running off to do that demo.
I don't use windows a lot, but I have several machines that duel-boot into Vista or Windows 7. Today, I needed to check something in Windows - using it right now, in fact - but I could not remember the username or password of an account. I did a quick Google and found a lot of pages that said to use your password recovery disk, but I didn't have one of those. So I thought 'there must be a way to do this in Linux. For ordinary people, there's Windows. For everything else, there's Linux'. And I remembered the Trinity Rescue Disk.
WebERP is a lightweight ERP system - one of the design goals is that it is simple, fast and runs on smaller hardware. The main contributor is in New Zealand.
It looks worth investigating further. But there are some problems. It relies on outputting PDF files - presumably for printing - but this shouldn't be to hard to fix. The most worrying thing is that there seems to be a battle of wills amongst some of the main contributors.