Hey,
 
Not sure what site I should ask this at really.  I am not a guitar player.... though I do use Sonar.  Anyway a lot of you play the guitar and this should is a pretty basic question.
 
Actually I do *play* the guitar, sort of, horribly... I've been taking lessons for a couple years.
 
I bought a travel guitar which has a pickup, I want to take it with me on vacation to practice.  I have a Dell ultrabook which I also bring with me, which has somewhat decent external Bose speakers.  So how can I connect the guitar to the computer so I can hear it?  Can I use a 1/8" to 1/4" cable or do I need some sort of box in between the guitar and computer?  (Links please!)  Do I need software? 
 
Sorry this is so dumb, I've been a keyboard player my entire life, I know nothing about guitars though I'm starting to find my way around on acoustic.  It's a whole different world... especially to try to pick it up later in life, no pun intended.

Your best option is a dedicated usb audio interface.  There are small ones the size of a key fob. Ideal for travel...
 
You could use a 1/4 to 1/8 adapter in the mic socket, but every alternative you find, working down from a usb interface, will be a degrading of the quality.
 
 
Edit to add:  That grammar is terrible...  "degrading of the quality"??  What was I thinking?  but I can't think of a better way to put it...

Can you post a link to a usb interface I should get?

Might as well get something like this perhaps then:
http://www.sweetwater.com/store/detail/MS2/
 

USB TO 1/4 in Jack

Hmm... that marshall amp is super cute, I may get that just for fun.  However wouldn't it be better to monitor my guitar through a $300 bose system than a $45 mini-amp?
 
That hosa cable is certainly a cheap option.  Does it work?  What software would I use with it?  I'd like to just be able to get a simple clean guitar sound, nothing fancy.

Some DI device (Line 6 pod of some kind, a Behringer crappy pod copy, etc.) will always sound better than plugging in directly - plus it will help match the impedance (usually high-Z coming out of the guitar to low-Z at the input to the computer).

The cheap stuff is not always the easiest or best way.
 
A nice dedicated audio only interface will be good.  However, the POD series by Line 6 and others will give you lots of options as far as sound. I use a POD on my recordings for guitar. I picked it up used on Ebay for about half the price of a new one.
 
A simple adapter from Radio Shack will let you input the guitar direct to the laptop. It will be really clean and generally thin sounding. Use a pedal to fatten it up and that might actually work OK.

Here.
http://www.fender.com/series/fender-audio/fender-slide-interface-greyblack/

It depends on how much you want to spend and how much and the variety of guitar playing you want to do. Guitarhacker pretty much covers it. A simple connection can lay a guitar part down and you can use plugins to enhance the sound. I use a Line 6 pod and it works for me.