You can set artsd to simply die after 1 sec. I've managed somehow to be able to play the sound in XMMS through OSS, system notifications through aRtsd and another stream of mp3s through alsaplayer. You can leave it on. It's not so critical. I suggest turning off crond, atd and fam. These are mainly used for maintenance, well suited for servers. As I said before, they're scheduling agents and FAM stands for File Alteration Monitor. Also, the KDE System Guard uses a lot of my resources. I don't suggest running it on regular basis . Use top, ps, killall and kill do do your killing. It's faster and you use less memory than KSysGuard. Also, KSysGuard launches a daemon KSysGuardd that should do all the statistics. I dunno if it remains started after you close sysguard, but you might check. The sound icon is KMIX, it doesn't use too much memory.

Run top to see exactly how much memory each process is using. You'll get around 200MB on X. As I know, the value at "RES" - resident memory is the amount of RAM used (my X is using 22 MB now and Firefox just above 36megs). For a graphical interface to top, you might see wether you have gtop installed. It pretty much does the same thing.