What Andy is saying is that your soundcard has to support Duplex audio. He's right, most Soundblasters will only do one or the other (record or playback) at one time. Most recording software supports monitoring, but if the hardware doesn't, you're out of luck.
What is hip?
Gear: Digidesign 003R / Telos Zephyr XStream ISDN codec / JK Audio Broadcast Host digital phone hybrid
PC: HP 6005 Pro MT PC running Windows 7 Pro 64-bit w 3 GHz AMD Phenom II x3 B7, 4GB RAM
DAWs: Sound Forge 10 Pro, Vegas Pro 9, Adobe Audition 3.0, Pro Tools LE 8.04, Reaper x64.