This is a very good free sample rate converter, better than Audacity:
http://www.voxengo.com/product/r8brain/
I bet the pro version is even better, but it is not free.

1.You should hear those commercial DVD-As in all their lossless MLP or uncompressed PCM glory on a DVD-A player! "Fragile" by Yes, "Brain Salad Surgery" by ELP, and "Gaucho" by Steely Dan are just amazing. IMO, in my listening experiences, SACD=shite. It is a little bit better than CD, but not the huge improvement that was expected. SACD even has less resolution than CD above 10kHz. DVD-A on the other hand is a giant leap beyond CD and SACD resolution. You can read more about SACD vs. DVD-A vs. CD here: http://sound.westhost.com/cd-sacd-dvda.htm
The author really blows the lid off the scam that is SACD.

2.Upsampling from 44.1 > 48 degrades sound quality (unless you have a cheap soundcard, then it actually improves it! I don't understand this). In one listening test I did on a PC with a good soundcard it was clear that the upsampled wav sounded a bit dull compared to the 44.1 wav. Most DAT recordings originated at 48. Then to burn to CD, they are downsampled to 44.1. Now that DVD-video is here, they are going back to 48. It would be great if everything that was recorded at 48 could be circulated that way, but it probably won't ever happen for at least half of the seeds.

3.I'm just a hobbyist too. My interest in sound really took off after I bought a pair of really nice 4 way speakers about 10 years ago. They were very revealing, and I realized that my system sounded like shit!!!.....unless I played vinyl. Vinyl/analog was the answer! It didn't help that I had one of the harshest sounding CD players ever made, I think, a 1994 Sony. I hooked it up again a couple of years ago and it was painful to listen to. Now with DVD-A I'm very happy with digital.

4.I agree, we started with analog > digital > more lifelike digital intended to sound more analog. The r8brain sample rate converter page says it supports bit depths of up to 64! I hope I get to hear 64 bit recordings in my lifetime. I kinda doubt it though. If you have heard an analog sourced vinyl record, though, you have heard the best sounding recording that will ever exist, unless you are listening to master 2" reels. I read about half of that article, I'll read more tomorrow. I've never heard of the R2R zero-oversampling DA converters! Sounds interesting.