Sound cards often produce a low-level hum... I found the iMic to be a better product for bringing in the sound than through a sound card.
Looking at your desire to record your old records to hard drive, I stumbled on something that may help you... You may be able to get a hacked version of an old program CoolEdit 2000 from here
, as well as some tips. I once owned CoolEdit.... can't find the software anymore and my need has long past. Good luck Lenny... hope it helps.