I am currently in the middle of encoding my entire vinyl collection to MP3. This is what I have learned:
Any turntable will do - you can use your old one so long as you have an amplifier to step up the signal voltage to the levels that your sound card will require. Alternatively, you can buy a pre-amplifier from Maplin and use that with your turntable.
I don't know anything about the USB turntables but, judging by their price, I expect that they will do a grim job of collecting the nuances of the vinyl. Much better to get a decent second-hand turntable off ebay. The time you will put into encoding even a handful of records will be completely undermined by using a rubbish turntable.
When you encode, if you have time to do it properly, then the best software by a long way is Wave Corrector (
www.wavecor.co.uk). This software is a bit complex to get the hang of, but once you hear the way it strips the crackles and pops off the background of a track like "In the Air tonight" by Phil Collins, your jaw will drop. It is like you just nipped out and bought the CD! Once you have set it up, it processes albums really quickly. Also (really cool) it can spot the quiet bits on an album and splits the output into separate files as separate tracks - saves loads of time.
When you save the file, I recommend you save as "ape" format. This is a lossless format but it is compressed. That way, you lose nothing of the detail. You can then go onwards and save it as MP3 as well (you lose a little detail at that point). Shame to lose all that beautiful music information in MP3. Also, APE is widely supported by the mainstream media players such as JRiver and WinAmp - and you can stream it around your house, too.
When you save as MP3 go for 320 Kbs, *not* variable - I am pretty sure the Comand MP3 system cannot handle variable bitrate MP3 files, nor can certain other players. The files will be bigger, but you are future-proofed. If you saved in APE, this won't matter, bacuase you can always cut another copy of your music library from your APE masters at any time.
After encoding, you will have a stack of unamed MP3 files - the best software for naming them is mp3tag - though it will also name the APE files. It is virtually automatic and pulls down track info from the web. You point it at a directory (created by Wave Corrector) with 11 APE / MP3 files in it numbered 1 to 11 and it automatically correlates these to the 11 tracks on the nominated album and renames them and tags them in one go. I tried about 30 products before settling on this one, it is brilliant.
That's it. Hope this helps. As you can see, this has become an obsession of mine.
Philip
Edit: One more thing - get yourself a second hard disk and a RAID card ((£60 for both). That way, you can never lose your music collection because of a disk crash. Believe me, after you have encoded 200 albums, you wont ever want to do that again.