I had your same dilemma last year when I was deciding between the two. Ultimately I chose the PS3 because it's an investment with long term returns because it's supposed to be a 10 year cycle console, whereas the Xbox 360 is a 5 year console that as of now (it's third year) is already showing it's limitations with multi platform games like DMC4, COD4 and Burnout Paradise presenting inferior graphics and framerate compared to the PS3.

Also, you have to look at the games you want to play. Seeing that you mentioned being a Sony fangirl, I can assure you that first party PS2 favourites like God of War, Ratchet and Clank, ICO and Shadow of the Colossus will not continue their lineage on any other console.

Furthermore, games like Metal Gear Solid 4 will unlikely find their way to the 360 due to it's hardware limitations and it's insufficient media storage.

Games like Final Fantasy XIII will equally be unlikely on the 360 because they require very high processing capabilities. Square Enix is working to put at least 4 of the 6 Cell SPE's into use to produce intense gameplay with Advent Children quality graphics. This is simply impossible on the 360.

Last but not least, with the advent of Bluray as the clear winner of the HD format wars, it would not be unwise to invest the cheapest yet most functional Bluray player on the market at the moment.

ps: 360's failure rate is another thing to consider.