Here's a run down of what each process is, to the best of my knowledge:
iPodService.exe - For iPods - probably comes with iTunes (and people wonder why I hate iTunes...)
NMBgMonitor.exe - To do with Nero, you can safely disable it with MSConfig
wmiprvse.exe - Windows Management Instrumenation - a system process.
ctfmon.exe - Windows Advanced Text Services, it can be disabled but it's harmless.
taskmgr.exe - Hint: When you close the Task Manager, this goes away
SNDSrvc.exe - Symantec - Related to Norton. There are a few services similar to this, which is why people say Norton products are memory hogs.
alg.exe - Application Layer Gateway service. Used when your PC is functioning as a gateway for other computers on a network, can be disabled with services.msc safely if this is *NOT* the case.
wuauclt.exe - Windows Update Client, for automatic updates.
avgcc.exe - AVG Anti-Virus control center. If you use AVG, personally I'd recommend uninstalling Norton.
iTunesHelper.exe - iTunes again... memory waste.
wdfmgr.exe - Windows User Mode Driver Framework, used by drivers which use this framework.
PCMService.exe - Apparently it's related to Dell Media Experience, can be safely removed with MSConfig.
ULCDRSvr.exe - Ulead DVD Workshop related service. It's probably required to run this program.
slserv.exe - "Installed alongside Smartlink communication products and offers additional support to the modem service." If you have a Smartlink product, leave it well alone.
nvsvc32.exe - nVidia Desktop Service. I'd actually recommend you disable this using services.msc - it can actually be a pain.
Hidservice.exe - Human Interface Device Service, usually started when you have fancy input devices.
CLMLService.exe - Cyberlink MediaLibrary, at first I thought this was spyware, but apparently it's to do with a media program. It uses a lot of RAM though, so I'd recommend uninstalling it (it's PowerDVD or something) and replacing it with something like
VLC which doesn't install any services.
CLMLServer.exe - Same again.
CLCapSvc.exe - I'm guessing, but it's probably the Video Capture service for Cyberlink programs.
avgemc.exe - AVG AV Related.
avgupsvc.exe - AVG AV Related.
avgamsvr.exe - AVG AV Related.
AOLacsd.exe - Probably related to AOL...
RTHDCPL.exe - Realtek Audio Control Panel
svchost.exe - Windows Service Host... there is more than one instance of this because most Windows Services spawn from it.
explorer.exe - Windows Explorer, also controls the start menu and desktop icons.
jusched.exe - Java Runtime Update Scheduler... I have this on my system, I can't figure out how to disable it
.
SDMCP.exe - Stardock Themes Customization related.
ccApp.exe - Norton product related.
spoolsv.exe - Printer Spooler (stores documents before they're printed).
lsass.exe - Windows Service - hopefully you've patched from WU, because lsass is the cause of the sasser virus (*BUT* if you've patched it is actually an essential windows service!)
services.exe - Windows Service.
winlogon.exe - Windows Service.
csrss.exe - Windows Service.
smss.exe - Windows Service.
ccEvtMgr.exe - Norton Product Related.
SPBBCSvc.exe - Norton Product Related.
ISSVC.exe - Norton Internet Security Related.
ccSetMgr.exe - Norton Product Related.
CLSched.exe - Cyberlink Product Related.
rundll32.exe - Windows Run DLL as Exe program, I haven't a clue what this could be running
.
System - Duh.
System Idle Process - I don't really know, but it gives an indication of how much free CPU there is
It's a big list, but apart from memory hogs such as Norton and Cyberlink stuff, I don't actually see anything nasty.