Confused about external hard drives

Looking to buy an external hard drive.
I see some use USB to power the drive.
Some have AC adapters.

Is there an advantage to AC adapters?

What i really want is a Hard drive that i can take to a friends house to
transfer files to there PC & not have to install software on there PC.
I also don't really want to drag AC adpters with me.

I would like a Hard drive i can just take with me & plug it into there USB &
use it.

Which type would be best ?

 

A 3.5 inch external hard drive will require an AC adapter.
Some 2.5 inch drives will work with the power supplied by a USB port, but it is best to use a cable that will plug into two USB ports. Such a device will use the signals from a single USB port but draw power from both ports.
Another possibility is to use a thumb drive since they can be had at a reasonable price up to 16 GB.

 

I want to use the device for backing up files.
Do still think a USB Flash drive would be best ?

 

This can be a tough call. Nothing beats a flash drive for convenience. Hard drives are among the most reliable storage medium; except for a relatively high failure rate for external drives, which many blame on a lack of a cooling fan. Hard drives are the most cost effective for large capacities.

 

Mike:
Don't need high capacity.
From what your saying maybe an Internal HD would be better.
Right now i have a Maxtor HD for backup in my old PC
But my new PC has a SATA HD
Would i be better buying a new SATA or getting an Enclosure for my old
Maxtor ?
Remember the Maxtor is old & it would'nt have a fan with the enclosure.

Whats your choice ?

 

I like internal drives in a well designed case better than external drives; I like to keep them cool.
A good way to back up data is over a local network. This won't cost you anything if both of your PCs have ethernet cards and Verizon gave you a router.
You can add another drive to your new PC, either SATA or PATA. Most new motherboards have at least one bus for older devices. Don't worry too much about using an old drive. A hard drive can last for many years, and you usually have warning before they die. They usually get noisy or slow before dying.
I have three hard drives in my main computer and also back up over my network. I use a flash drive when I take my laptop on a trip.