Using Mobile InSouth Africa

justustwo19

Hi can anyone help me with advice on sim cards and unlocking mobiles.Im off to South Africa for an extended stay(+6 months) and i want to know the best way i can stay connected over there. I have an XDA11i (PDA type mobile) and a Samsung S400 which are both on o2 pay as you go.Ive been told by a friend over there that the best network to use is Virgin mobile(presumably this is a S.A variant of our Virgin?). I will probably buy a sim card for that network when i arrive(could i buy before i arrive in S.A ?). Now i believe i will need to unlock both my devices but how do i check if i need to, or go about doing it ??.Would it best be done here before i go (if possible)so it is ready on arrival or should i do it over in S.A. ?
I went to Carphone Wharehouse to ask a guy and he said that the XDA11i should already be unlocked for any network in Africa under a roaming agreement, but would doing this mean using my current sim (with expensive call charges !!)??. I did go to Ghana West Arica last year but i couldnt (or at least i didnt know how) to use the XDA11i(it was actually a XDA11s i had then but basically the same). I tried it on my UK sim (o2)and a friends Ghana sim but couldnt use the XDA.
I will be mainly using mobles for internal S.A calls but very occassionally back to the UK.
Any help and advice much appreciated