I am using TerraTec PreAmp Studio. The signal from the turntable doesn't have to be amplified, so it can be connected directly to the turntable pre-amp out, and PC input can be adjusted via the box that comes with it, to give a sufficiently high enough recording volume. The pickup impedence input can also be altered to suit the cartridge. I found that when I tried Magix Audio Cleaning Lab 3.0, the output from the pickup wasn't high enough to give me sufficient input volume directly from the turntable pre-amp out. My kit (now 18 months old) came with 'Cool Edit 96', so you can do sound editing to some extent with that, and it also came with 'Sound Laundry' which you can use to clean up any 'dirty' recordings.
audio cleaning lab gets it signal from the phono leads or headphone socket from the amp. its got all the bits and pieces in it to clean up the recording etc etc, im planning on starting to do my vinyl at the weekend.
I've been transferring my large LP collection to CD over the last nine months or so. I connect the stereo Tape Output from my HiFi system, via good quality screened leads, to the line inputs of my Creative Labs Soundblaster card. The editor I use for recording and subsequent cleaning of the odd Pop and Click is Goldwave. This editor can be downloaded from Goldwave.com and is fairly intuitive to use.
I would add that it is important to have a good quality Audio card in the PC : Audio interfaces which are incorporated within the Motherboard are liable to produce poor results.
willum has the answer for connecting up which is the same as my system.
I use a programme Called LP Recorder to record to Hard Disk and a Programme called LP Ripper which I use to split the one .wav file back into separate tracks. Brilliant programmes. Both can be downloaded from click here