So, Finally I have decided to buy a 360, but I have a few questions I would like to ask first.

1. Is a 20g HD enough?

2. Is it cheaper to buy a Arcade version and a separate HD?

3. Should I stay away from used consoles?

4. How long warranty is there?

5. What would you recommend for someone who would like to spend as little money on a 360 as possible?

I am looking for a US version

The Pro models in the U.S. are 60gig now
3 year warranty for the RROD which usually covers all the issues
Don't buy a used one.. stay away from used 360's!!

If money is an issue, then just buy the arcade... save some money and buy a HDD a couple months later

          ^^  That about sums it up.....nice post.

I would wait until May and then get the Elite bundled with Halo 3 and Fable 2 if you can afford it.

With a three year warranty you will have the peak of Xbox 360 gaming for many years to come, and both of those titles are absolutely EXCELLENT!!!!

What is the difference of Silver and Gold Xbox live?

I agree about waiting for the Elite bundle, Halo 3 & Fable 2 are two of its best games. And with a 120GB hard drive you'll never have any space-related worries.

As for your other question, you have to pay for Gold XBL so you can play online which is $50 a year. Silver is free but you wouldn't be able to play online with it.

Go buy a Nintendo Wii.

360 (much like Ps3) is an expensive investment.

You have to pay $50 to play online, EVERY YEAR. Then another $100 if you want Wireless connection.

Shop Around. I haven't paid $50 in years

Just get the Pro Unit it comes with everything you need and it has a 60Gig hard-drive.