Thom, If it's a Realtek sound card, you really need to buy a better audio interface. Realtek is usually cheap on-board audio designed for use for things like video messaging, not for pro audio.

A preamp might help with levels but you'll still struggle for quality, you really need some sort of device from a known decent maker.

What you get depends on what exactly you want to record, what you want to connect and what mics you are planning to use.