I am using my xbox 360 with the same converter for more than 2 years, without any problems. Just buy a converter with at least 300W of power. The weaker ones will die and might take your xbox with it.
Buy a few live gold cards before you go, so you won't have to use your credit card for purchases - do buy them in US, because the card codes are different from one region to another, so you will not be able to use the local ones.
If you want to use your xbox fully, you should have it connected to a hd or hd ready tv, so no worries about pal/ntsc anyway.
