Andrew Morton's low-latency patches provide an easy way to reduce performance latency significantly at the kernel level (www.zip.com.au/~akpm/linux/schedlat.html). The article “Achieving Low-latency Response Times Under Linux” (by yours truly) describes the process of configuring your own system for low latency (linux.oreillynet.com/pub/a/linux/2000/11/17/low_latency.html).
The Pd sources and binaries are available at Miller Puckette's Pd home page (crca.ucsd.edu/~msp/software.html). More information about Pd can be found at www.pure-data.org. Information about the Max programming environment is available at www.cycling74.com. Development of jMax is sponsored by and hosted at IRCAM (http://www.ircam.fr/equipes/temps-reel/jmax/en/index.php3).