A relative is about to travel to the US, and is looking for the best method to get mobile data access while over there.

In NZ, she's been using a Telecom NZ mobile data card (Sierra datacard, PCMCIA I think, I'll check the model number and post back) for travel around NZ and is generally happy with it. Her laptop is Vista.

She's been advised by a Telecom rep that her best bet for roaming access in the US is to switch to the new T-Stick. I've been asked to look into the options - looks like the T-Stick is a fine device from the reviews on the forum here, but will it really give her any advantages when roaming?

Apart from the security of knowing she has a renewed 24-month contract with Telecom? ;)

I can see some alternatives:

• She has her existing Sierra datacard, which is probably best unless there are known issues with it in the US. Her laptop already works, and reconfiguring it the day before leaving for a new device introduces the chance that she'll need support when she gets there.
• Telecom have suggested the T-Stick, but this might well just be an auto-response from the Sales department rather than technical input. If there's a good reason to switch, I'd be keen to hear it.
• I have a disused Vodafone HSPDA card; she could take that and grab herself a local GSM connection stateside. (They do have GSM, don't they?)
• Land in the US, sign up with a local mobile provider and get a data card there. If so, which is the best option? And will that hardware be of any use to her on return to NZ?

I'd appreciate any input from people who have travelled to the US and tried any of these options out, or can give some knowledgeable input on the best approach for a Kiwi travelling to the US to get roaming data access.