please help with midi sound card / synth / keyboard setup

[earle]

would be grateful for some advice, although I've been producing for a while I have no knowledge of midi.
up to now I've used reason with a fairly standard soundcard and usb keyboard. I've just ordered a hardware synth (a sidstation) and need to connect it to my pc. I plan to use sonar, and rewire it to reason.
question - what is a good but cheap (under £100) soundcard to be able to do this? I want to be able to keep the keyboard plugged into the PC and not directly to the synth.

Please help!

[earle]

also my keyboard has a usb out to my PC and no midi - do I need to get another keyboard with midi, or will the sondcard take care of all midi?
thanks