Quesion regarding home recording and PCs?

Sound card is important but not the only cause of latency. The RAM could be an issue as can be the processor and more often than not the hard drive. I have found that hard drives that spin at 5400rpm are terrible for home recording and that 7200rpm usual works out the best. Have you tried a mic directly into the sound card using the 3.5mm connection? There may be delay using the usb mic that you currently have so it would be worthwhile trying a 'traditional' mic first before you go any further.