I'll come clean straight away, I work for New Balance.
About 40% of the shoes we sell in Europe are produced in our factory in the UK (it's near Workington in Cumbria). It's definitely not a sweatshop, I worked there for a year. The balance are imported from the Far East, we employ a third party company to 'audit' the factories we use for their 'human rights' record, but this is all handled by the parent company in the USA so I've really no idea what standards are applied - there may be more info on the website (www.newbalance.co.uk for us, www.newbalance.com for the international site).
There are also 5 factories in the USA, again they produce about 40% of the shoes they sell in the USA there (but don't quote me on that figure, it may be more).
As far as I'm aware (and I'm pretty sure) we're the only major manufacturer who still produces in Europe (PB Walsh used to have a factory in Bolton (I think), don't know what's happened since the company was sold).
There are magazines you could look to for recommendations as well - there's certainly one called 'Ethical consumer' plus there's probably plenty of info available on the web.
If you want a good read on the whole subject of Globalisation/ethics/branding etc I'd recommend 'No Logo' by Gloria (?) Stein.
I'll stop being a corporate mouthpiece now and go back to being just a runner....