Ok I'll give you a list of ones you can shut down without harming anything. If you feel you need one of them just don't uncheck the box. Once you are done unchecking the boxes just close the program and restart your laptop.
Here's the list:
ECenter
HP Software
ISUSPM Startup
ISUSScheduler
PCMService
QuickTime
Adobe Reader
Digital Line
HP Digital Imaging
QuickSet.lnk
AROReminder
Dell Support
DellTransfer
Steam
Unless you use Steam for CS, TF2 etc an absolute ton I would recommend turning it off. It uses quite a bit of resources and takes up bandwidth while running. You can also turn off the Dell wireless utility if you want. Windows wireless setup is pretty good. If you always use a mouse and not the touch pad turn Synaptics off.