Plan to buy cell phone

Hi guys this forum is big!

Anyways i need advice on buying a new cell phone or pda.

I want to log into MSN and Yahoo messenger on my mobile device at the same time surfing the web. Maybe more IM programs if it's possible.

What cell phone or pda brand is better for that type of work.

I'm planning to open a web shop but i don't want to get tied down to my pc so i go on my pda or cell phone so i'm truely mobile.

I need:
Brand name:
Price:
If you have time why:

Thanks for everybody's help