Ipad - which one?

Hey all,
quick question.  We leave next Weds for Siem Reap for two years (provided the volcanic cloud over Melbourne doesn't hang around any longer).  I was planning on buying an ipad to take, as I don't have a laptop and thought it would be useful.  Just wondering if anyone uses one there, and if so, whether they rely on wifi or 3G.  If it is only wifi, is there really any point having one, as I guess the portability factor is the main reason you would want one, and if you can only log onto the net where you had wifi access it seems a bit limited.  I was told that there is good wifi access in Cambodia via little USB sticks, but ipads don't have USBs - is there internet access via a SIM card or just wifi through landlines.

Any advice would be useful

Ta
Jacqui

Hello i have both wifi and 3G it is very interessing to have both :)

Thanks Dominique,
Could you tell me what part of Cambodia you are in (i.e.: is it remote or are you in PP) and how the 3G works (i.e.: SIM card or what?) 
Thanks!
Jacqui