Good decision, Himumu.
I was just about to do the same, only I discovered a few days ago that the 360 can be used in conjunction with an external USB HDD to play HD movie rips bigger than 4 gigs. I'm thinking of putting it in my closet once I've completed Ninja Blade, as I'll get a 25 inches-long HDMI cable to use my PC to play those files.
However I don't think you'll really compromise on graphics all that much, since admittedly most recent multiplatform ports on PS3 look practically identical to their 360 counterparts, as evidenced by the likes of Dead Space, Star Wars Force Unleashed and others.
The biggest factor to me is the fact that practically all big 360 "exclusives" get ported on the PC. It's already my de facto platform for gaming anyway, so why would I cope with inferior graphics, resolution and effects? So these Alan Wake, Mass Effect 2 and whatnot would be foolish to play on 360.
I'm not really a partisan of the system, but at least on PS3 the exclusives are TRUE exclusives and they're only available there. Plus Sony takes first and second party development way more seriously than MS, and 2009 looks to be another very promising year.
And as you said, Microsoft's bullshit DRM policies truly infuriate me, along with the inability to buy the exact amount of Microsoft points that you want. If I buy a game that costs 1200 points I don't want to be forced to spend MORE than that! The R-Type remake looks pretty sweet but because of these reasons I don't know if I'm going to get it anymore.