For the LP material, first make sure you have a good turntable. Look around, and you will find that there are now audiophile-quality USB devices intended ONLY for capture from a turntable. (They have a good-quality preamp built-in.) Of course, you will probably want to apply a "scratch and pop" software filter after you've captured it.

In general, external USB devices stand a better chance of doing a good job than internal cards. Internal cards have a horribly noisy electrical environment to work in. Built-in sound on mother boards and notebooks are notoriously noisy - particularly on inputs. (Most today are not bad on outputs.)

The humble Soundblaster, in any reasonably-recent incarnation, actually isn't bad, (any Audigy-series are decent) though "golden ear" audiophiles will beg to differ. The very early Soundblasters were awful, and stuck them with a bad reputation early on. The are more professional solutions, though, either internal or external. Check a professional sound catalog, such as BSW.

Wish I could be more specific about products, but I don't have a need for this myself, and am not that familiar with current products. I just have enough knowledge on the subject to be dangerous. I was involved in developing the first sound card for notebooks, and was the one stuck with doing the audio testing.