Business Solution, need your help!

[trickyireland]

Hi everybody, please bare with me this may be a long post.

I will start from the beginning!

I run a small business in kent with only 2 employees.
Our current network set up is

1x SPV M5000
1x HP IPAQ H6340
1x Nokia 6230

I need a solution that will enable me to set up remote networking to the company servers, while syncing with exchange contacts, email, calender and tasks etc.

I also need to have the devices connect to the servers while over a gprs connection and automatically grab any new emails and send them too with little interaction from the user.

I am currently with Orange UK, i have all my voice calls using the nokia 6230
and i have a GPRS bundle included on the account which enables me to use 10mb per month.

I also have tomtom navigator 5 on the ipaq h6340 which also uses a gprs connection for updating the latest traffic info.

Now what im thinking of doing is having the following set up:

2x spv m5000
2x nokia 6230
0x ipaq h6340

I want to do away with the ipaq and make room for an additional spv.
I wanted the spv's to carry data only which will be connected constantly always updating its self to the company network no matter where the end user is in the uk
The spv will also have tomtom navigator 5 on them acting as a navigation aid to the end user.
I would also need the spv's to switch from gprs connection to wifi once the company hotspot is picked up.

The nokias will be used purely for voice and text calls.

Now the way i work this out is i will require a total of

4x orange sim cards all connected to the network, 2 of which will have a heavy gprs bundle attached to them but little or no free voice minutes as i dont want them being used for voice at all.
And the other 2 will be purly for voice and text.

Now you may of already realised i am trying to emulate a blackberry device in a way. Constantly connected gprs connection etc.
All i need to know is am i going about this the right way?
Do you know anyone with a similar set up?
Is there anything i need to set up on our small business server 2003 / exchange 2003 to get it all working ok.

Blackberry uses push technology and this is what i am trying to copy however in a windows environment.

Any help on this would be gratefully received.

Trickyx