On Monday, GameStop exclusively revealed to Level Up that during the first week that Grand Theft Auto IV was available in its U.S. stores, 64 percent of all copies sold were for Xbox 360 and 36 percent for Playstation 3. We sought reaction from both Microsoft and Sony to GameStop's results and our impromptu analysis, a portion of which we shared with you on Monday. Today, we're publishing our conversations with the two console manufacturers in their entirety. First up is Aaron Greenberg, director of product management at Microsoft. Here's what he told us via email:

GameStop has exclusively provided me with the percentage split on their first week sales figures for Grand Theft Auto IV. According to them, 64 percent of the copies of GTA IV sold were for Xbox 360, while 36 percent were for PS3. Given that Grand Theft Auto has been primarily associated with Playstation platforms since Grand Theft Auto III in 2001, are you surprised that the Xbox 360 was able to corral this high a share?

I think many people have been surprised to see how well GTA IV is selling on Xbox 360 given the history of the franchise. These sales results add GTA IV to a long list of franchises that have switched over from Playstation to find a new home on Xbox 360 similar to what happened last year with titles like Madden and Guitar Hero. As you have covered on Level Up in the past, the majority of third party franchises are being developed first on our platform so they end up playing best on Xbox 360 and when you combine that with Xbox Live, we expect this trend to continue as more multiplatform releases hit the market. With that said, it is fantastic to hear that we beat PS3 two to one on Grand Theft Auto sales from a major retailer like GameStop.

Do you expect this gap to widen or narrow over the rest of the year, and why?

It's tough to say, I think GTA IV will have a much longer tail than some of the other blockbuster titles that have released on our platform. I expect that even this holiday as a lot of new console buyers enter the market we will see GTA IV remain a top title they purchase for the console. Then you also have to consider the excitement and buzz that will be generated when Rockstar starts to promote more details around the exclusive episodes coming to Xbox 360. However, it is clear that there is going to be a completely new Grand Theft Auto IV experience coming to Xbox 360 this fall and I think it is fair to expect that it is going to be a driving factor for another big round of sales of the game.

I did a little math of my own with the help of NPD, which says that through the end of March 2008, 9.9 million Xbox 360s and 4.1 million PS3s have been sold in the U.S. That's a total of 14 million units, of which 70.7 percent are Xbox 360 and 29.3 percent are PS3. When I compare this to GameStop's split of GTA IV sales--64 percent on Xbox 360 and 36 percent on PS3--it's clear that GTA IV underperformed on Xbox 360 relative to Microsoft's pre-April installed base, while it exceeded expectations on PS3 relative to Sony's pre-April installed base. What's your reaction to this, and to what do you attribute this result?

Heading into the release there was a lot of expectation that this would drive many of the PS2 owners into the next-generation for the first time. While these guys were up for grabs, we know that they had a history with the Playstation brand and so we had a lot of work ahead of us to reach these consumers and welcome them into the Xbox community. To see sales of the game leading on Xbox 360 and a two-to-one ratio of the title at an account like GameStop is a great sign that we are moving the needle here. While we expect May console sales to be a better barometer for the impact of GTA IV, we did hear from retailers that Xbox 360 had a larger lift across the channel the last week of the month than PS3. We are incredibly happy with these early numbers and think it shows that consumers are learning that Xbox 360 and Xbox Live are the best place to play the game.

What impact do you expect the Xbox 360 exclusive downloadable content will have on the relative sales of GTA IV on PS3 and Xbox 360? Why hasn't this content been mentioned in any of the TV ads for GTA IV that are being supported by Microsoft's co-marketing dollars?

I expect that the exclusive downloadable episodes will have a substantial impact on Xbox 360 consoles sales as well as sales of the game on our platform. We focused our launch marketing spend more heavily in Europe given the importance of that market for us. As you know, we lowered the price of the Xbox 360 across Europe in advance of the launch of GTA IV and you can now buy an Xbox 360 in Europe for almost half the price of a PS3. We also launched a massive advertising and marketing campaign in Europe to promote the Xbox 360 version of the game. The results have been incredible so far as we have seen our console sales double, which is great momentum for us given our now more than 1 million unit lead over PS3 in Europe. But I can tell you to keep your eye out for additional marketing and advertising support for the game in the US throughout the year, this remains a very important franchise for us as we grow our installed base.