I'll be spending a week or so in Thailand, based mainly in Chiang Mai, and would like recommendations and advice on which SIM card to buy, so I can just plug my mobile phone into my laptop for internet access. Looking for suggestions on which company offers the best balance of cost versus speed/performance. It's been a while since I was in Thailand, and I'm a bit out of touch with the various providers. A friend has suggested 12call, but are there any better options available?

Any assistance would be greatly appreciated.

I used 12call some time ago seemed to work ok, a bit slow but they all are. If you dont want to down load load's, it's as good as any. I think 250+ hour's a month 500bt.

You can get 3G in Chiang Mai with AIS, not sure of current prices but you can buy a sim at any phone shop then you will need to ring AIS to setup the 3G interent.