nijuu: I used to want to support Impulse til i found out they are one of the worst offenders regarding regional pricing. Many of the AAA games are not available to the Australia region....
They're comparable to Direct2Drive in that regard. I'm not sure if it's the case, but it's like Steam have actually bothered to try and get deals with the international distributors, but Impulse and D2D decided that they'd deal with the US distributors or forget about it.
That's not likely to improve for either company now that they've both been acquired by gaming companies with an almost exclusive US presence.
Impulse/Gamestop also occasionally doesn't follow Steam's lead with regards to US/Australia pricing variations, so it's worth having it installed (or the website bookmarked) just to keep an eye on the sales. I picked up Arkham City for AUD$25 a couple of weeks back, 75% less than it's currently going for on Steam.