This is usually down to software, not hardware. Close as many running applications as possible, especially Internet connections and e-mail clients. The reason you get the skips, jumps and gaps is because the recording program priority is overtaken by another running application. For example, if you get a skip or a jump at fairly regular intervals your recordings could be being interrupted by your e-mail client accessing the network looking for mail.

The next option is to defragment your hard drive. If you've had the PC for a while and have never done this then the current data on your drive will be fragmented which means that it is spread in different places on the drive and not all together. When you record a track from vinyl the recording software looks for gaps on the drive to save the info which will return jumps and skips.