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Might I suggest that you use a USB to TTL serial adapter available from eBay for only a few pounds/dollars, these work well provided you do not want very high speed. If you get one of these type modules I recommend that you get a FT232RL type as they have Windows 8 drivers as well as handshaking.
In any case you need an application on pc side.
My suggestion is that either use usb-hid class or usb-cdc class
First make your usb device using pic and test it with pc.
For usb hid class you can use hid terminal from mikroelektronika and for usb cdc class you can use hyperterminal.
After testing your device move further.
If you use usb hid class then there is a usb hid tempelate in visual basic from which you can develop your own gui.