I own every console dating back to the NES, so here is my take.
I like Live over PSN, plus I have more friends who own a 360, so I buy all my multiplats on the 360.
Multiplats are generally better on 360 (including GB according to IGN's review,) so I get all multiplats on 360.
If I didn't own a 360 or PS3, I would still buy a 360 since it has the supposed better version of GB, plus I have more friends on 360, so don't want to feel left out.
If I chose a 360, and was trying to stay within 399 bucks, plus tax, I would buy the Pro system (299,) and buy the cheapest Blu Ray player on the market, which I hear is 129 bucks, or cheaper, which would equal out to about the cost of a PS3 after tax.
That is what I would do had I had a lot of friends who are on Live, rather than PSN.
However, I own both systems, so for me it's -
Ghostbusters best version on 360.
Ghostbusters Bluray for my PS3 (Best Buy is selling it for 20 bucks when released next week.)
Hope any of my info helps. Oh and I hate console wars too… They are fake, and started by fanboys who are too broke to be real gamers, so they bash the systems they don't like, instead of just enjoying the system they chose.