Any suggestions -Vista / internet data card - ?

Any suggestions - internet data card - Pay as you go Service?
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I have 2 questions.

1. I am in the process of buying a laptop ( Vista). The new laptop
does not have a
slot for an internet datacard to be inserted ...can only accomodate
a USB device for internet data service. So I will need a service that
offers the USB device. I am using T mobile (USA) ( US 49.99 per
month ) now but they do not offer a USB device in lieu of the
internet data card.
So I have to find a new service. Any suggestions of an economical
service ?

2. Since I hardly use this service - maybe once in 2 months ( for
about an hour or so ) and have been paying for this service for over 2
years! What a waste.
Is there a company in the US that offers this service on a Pay as
you go basis (AND hopefully also the USB device instead of the Data
Card ) ?
This would reduce my expense substantially.
Any suggestions ?


Or can anyone suggest any other economical service / option ?


Not being in the technical field and having little knowledge and
experience of integrating different components, technologies etc I
would prefer a company/package that makes it simple for me to get the
service going without pulling my hair out.

Any recommendations would be highly appreciated,

Ayesha Hill