I don't know about the electric bill part.
Yes, memory management is better.
Yes, you can use the CPU to its full potential.
Yes, boot time can be faster.
Yes, you can dual boot.
There is a howto on here for repartitioning the drive without destroying information.
You may want to install Linux in a virtual machine so that you can adjust to it before installing it physically as a host.
i am currently running xp on my hp desktop replacement laptop (pavillion zx5040us), which has an intel pentium 4 2.80ghz processor, 512mb of ram, an ATI mobility radeon 9200 graphics card, a broadcom 802.11b/g WLAN wifi adapter, and a 60gb hard drive.
also, if i switch, will i be able to manage my memory better? will i be able to use the potential of my processor, as well as the potential of the other components listed above, better? will my boot up times be faster?
also, i ask the same questions if i were to dual boot it with my xp. im sorry if i didnt ask my question well or if i didnt give enough details.