Help: options for connecting TP to PC

[featips]

I remember the first time when I connect my TP to my laptop (vista), it came out a option selection:
(1) ActiveSync
(2) Disk drive
(3) Internet sharing

I choose (1) and also check the box of 'not ask again'.

Now, the problem is, as long as the device is connected to PC, a connection with mobile device center is automatically established. Then, I can not use the EV data plan. As long as I unplug the USB cable, I can use EV data connection again.

So, now I want to switch the selection from 'ActiveSyc' to 'Disk drive'. Now, my questions are:

(a) How to get the selection interface again? Since I selected 'not ask again', I can not access it with plugging USB cable.

(b) Every time when I want to install software through ActiveSync, I shall choose (1). If I want to use data plan and also charge phone, I shall choose (2); If I want to do phone as modem, I shall choose (3). So, in suumary, I shouldn't check 'not ask again', instead I shall make the selection interface comes out each time when I connect the device to PC. Is mmy understanding correct?

Thanks a lot for your help.