It all comes down to opinions.
Like I said, if you already game on your PC, and prefer gaming on your PC, then a 360 wouldnt do much good since most 360 games comes out to PC.
The DS is not actually more superior than the PSP, it's all about opinions. They each have their own unique games. My brother plays his PSP more than his DS, and he still plays his PS2 more than our 360.
Kinda funny on how I am the only one suggesting the PSP over the 360.
I had more epic times with the PSP than the 360, my friends, brother and I always have fun when we play games like Monster Hunter together, we spent 4 hours together playing that game and we didnt even notice.
Get what you feel you would want, don't get what was suggested most. If you think the 360 will give you more fun, then get the 360, or vice versa with the PSP or any other systems.