my birthday is coming up early march and i still can't decide whether or not to get a 360 or a ps3. i already have a wii and i want to get another console. i still play my wii everyday but i want to play sports games like fifa 08 and nhl 08 and other types of games that the wii doesnt have. so i need your opinions on which console i should get, and please back up your reasons. 

Just buy another Wii then, that's still considered another console.

What I can say is this....since the PS3 and the 360 share most 3rd party games,go with the system that has the 1st and 2nd party titles that appeal to you.

Yeah, it depends on what 1st party games you like. Halo or Uncharted etc...

I suggest the following:

1) Look at each consoles library then look at current release schedule for this year - determine which appeals to you more vs what you play on Wii (one caveat on this is do you have a decent gaming PC? If so then consider whether you would prefer to play games like Bioshock / Mass Effect on PC or 360, if PC then drop them from 360 games list when comparing)

2) Consider online vs offline - are you planning on playing online? Do your friends already have console for online? If so and you want to go with friends follow their choice so long as it doesn't affect point 1) above. If you want to go online and don't care about friends then its cost vs promise. Online with PS3 is free but 360 has better online but you pay for it

3) Consider non-gaming elements - is this console only really for games or are you thinking of watching movies, storing content, etc? Are you interested in BR? If so then PS3 might be better, if not then 360 is probably more in line with what you want from the console

4) Consider reliability/risk - the 360 should I believe still be considered as a higher risk from rate of failure point of view. Does this matter? Do you want more solid console or are you happy with getting console replaced? If you don't like risk then PS3 is better choice than 360 for reliability

If the above fails toss a coin and don't blame me whatever happens...

For the record I wanted solid console, non PC centric games potential, DVD/BR movie playback and free online so I got a PS3. I also have a PC for games and removing the games such as Gears, Bioshock and Mass Effect from the equation I realised most 360 games that were exclusive that I wanted to play I could do so on PC while games like Uncharted and R&C would not come to PC so in fact the smaller PS3 library was actually larger from my point of view than 360's.

I would get a PS3, blu ray and Sony > Microsoft.

Well just look at the exclusives and determine which ones you like.

Why don't you get yourself a gaming PC? :)

 Yeah listen to fazz. How much money do you have to spear. If you have at least 700 dollars then go with a gaming pc. If not then just get a ps3/360. 

Reasonable has plenty of great points.
He is a very reasonable person (ZING!)
..
Another thing I'd like to point out.
If you already have a great gaming PC, then you really shouldn't get a 360 since most games are shared across both platforms.