I borrowed 5V from the USB line of a data acquisition card -- it is somewhat
noisy so I put a 100uH choke and a small tantalum on the line -- it works.

You can get excellent noise performance (far exceeding the Wetzel modified
LM317 circuit) with Linear Technologies LT1763 and LT1964 ultra-low noise
regulators -- they will do 100mA on their own and can be used to drive a
pass transistor if you need more juice. Unfortunately, post regulating any
digital supply for analog circuitry burns up watts.

fwiw -- while dual bypass caps aren't a good idea for digital circuits
(because of the ringing aforementioned) -- in analog they are recommended
for certain low noise apps because of susceptibility to EMI and RFI.