The best SOUNDING card for the money is the E-mu M series (i.e. 1212m). They have the best specs and the most transparent sound. They use the same converters as Pro Tools HD systems. Hard to beat for the price. But they can be a pain to set up. The software is useful and powerful, but complicated.
Lynx cards aren't cheap, but they're sort of the Rolls Royce of sound cards. DAL CardDeluxe cards are close behind.
M-Audio cards are a good buy if you just want it to work. The converters aren't quite as outstanding as others, but they're easy to set up and inexpensive. Compatability is better than with just about any other company. As a bonus, they'll allow you to run Pro Tools M-Powered. And the sound, though not as pristine as E-mu, is worlds better than any 'consumer' card.
Echo cards are also very good. Generally, the converters are very good, as is the compatability. The connectors are rock-solid. And the price is right!
As for other suggestions, larger fans (120mm) make less noise in the case. SATA hard drives are better and often quieter. And 10,000 RPM drives are generally the quietest performers. Antec makes silicone gaskets for fans and drives that can cut down the noise a bit, as well.
Emmett