1. Openware's LiveUpdate component comes bundled with a few different programs, so I can't tell you exactly what program that you installed may have put it on your system. LiveUpdate does what it's name implies: it provides auto-update functionality via the Internet for the programs that use it. It isn't malicious, and it's not essential either; it's up to you whether to have it running or not.
2. cthelper.exe is a component of some Creative Labs soundcard programs. It is not malicious, but it's also not essential; you can safely disable it if you wish.
3. DigiChat is also an optional program; remove it if you want.
4. qttask.exe and realsched.exe are two other non-essential components that don't need to be run at startup.
That said, you can safely have HijackThis fix the following:
O4 - HKLM\..\Run: [CTHelper] CTHELPER.EXE
O4 - HKLM\..\Run: [QuickTime Task] "C:\Program Files\QuickTime\qttask.exe" -atboottime
O4 - HKLM\..\Run: [TkBellExe] "C:\Program Files\Common Files\Real\Update_OB\realsched.exe" -osboot
O4 - HKLM\..\Run: [Openwares LiveUpdate] C:\Program Files\LiveUpdate\LiveUpdate.exe
O16 - DPF: DigiChat Applet - http://host8.digichat.com/DigiChat/...s/Client_IE.cab