You very much can use the POD going just into the computer. If that is all you ever want to record, than that is all you need. However, I can't imagine you wanting to record just your guitar. With an interface, you can do vocals, and pretty much any other instrument. With the interface you attached, you have the ability to use MIDI, as well as having a dual headphone amp among other things. If you have the means, I would say go for it. One thing I will say is work within your intention. If you feel recording more is what you want to pursue, than it certainly does't hurt to have more than what you need to allow for that growth. That interface will allow you to do and record pretty much anything you need too.

There are cheaper ones out there that will have fewer inputs, but you can record guitar, vocals, and use MIDI; which pretty much covers it. Here are a few others that are cheaper. Again, the one you are looking at is great and if you can get that; do it. These one's are simply some cheaper alternatives that will also meet your needs as well.

Presonus Audio Box

M Audio Fast Track Pro 4 x 4

List of Several DIfferent USB Interfaces