http://www.ptlcomputers.co.nz/
Ive bought or recommended to others who have bought from these people maybe 10 times. As with any thing 2nd hand you sometimes get problems but they have fixed them up pretty quick when its happened inside the warranty.
Or buy a netbook like
Mini 210, Atom N450 1.6 GHz, 1GB RAM, 250GB HDD, 10.1" TFT, No optical drives, WLAN, Bluetooth, Win 7 Starter, Black $768.38
http://www.ascent.co.nz/productspecification.aspx?ItemID=385013
You can get cheaper ones with XP on but I would suggest win7. It might cost a bit more in the short term but you will save money and time with a new laptop/netbook. If something breaks on them theres very little in the way of user replaceable parts.