I am going to copy my post to a user a few days ago who also enquired about what system to get, and I will extend this to answer your questions.
Deciding between PS3 and XBox 360 depends on:
- if you're willing to pay for XBL (although XBL has a better online service than PSN)
- what exclusives you prefer (e.g. there's Metal Gear Solid, God of War, inFAMOUS, Little Big Planet and Uncharted on the PS3 but L4D, Halo and Gears of War on XBox 360).
- if you want to use the Blu-ray player aspect of the PS3 (both consoles play DVDs but PS3s play 2D and 3D Blu-rays)
There are no Resident Evil exclusives for either console, the only current disc release for them is Resident Evil 5 (I recommend you get Gold Edition if you want the extra costumes, online modes and story modes). Operation Raccoon City will be coming out for both consoles (sometime next year?) and yes, both Resident Evil 4 and Resident Evil - CODE: Veronica are being re-released in HD next month for both consoles. However, Resident Evil: Director's Cut is currently only downloadable from PlayStation Store (for about £8).
Both consoles can have their problems, but I've known PS3 to not have as many problems as an XBox 360. But they're both great consoles, I own a PS3 and my fiance owns an Xbox 360.
If you have spare cash: get some Resident Evil skins for your console on eBay!!
I wouldn't recommend selling your PS2 if you have PS2 games you want to play on it. PS2 games DO NOT work on the PS3 (PS1 and PS3 games do though, and it will also take DVDs and Blu-rays). You won't get much more than £20 for it.
I would recommend trying consoles first hand if you can. Try them at your friends' houses, see what feels best, what exclusives you prefer etc. What consoles do you friends have (if you want to play online you may want to get the same console as your friends so you can all play together)? Look at the exclusives' gameplay vids, what looks best to you?
I have a PS3 because I love to use the Blu-ray player, my friends/brother have PS3s, I don't have to pay for the online and I have grown up with the PlayStation. Although I LOVE L4D I prefer the PS3 exclusives, and in any case my fiance has an Xbox 360 so I just use his if I want to and he uses my PS3

that's just what works for me, not saying it will be the same for you! They are both great consoles
Christmas sales will be a great time to get them as shops usually have great console deals for the holidays. I got my 320GB PS3 last Christmas in a special deal at Argos (I sold on my old 40GB PS3) for about £285, and it included 2 free games, a compatible extra controller (which I sold on with my old PS3 - I already had a spare official controller

) and a freeview converter thingy. I don't know if you're from the UK or not but I recommend, if you want to buy a console pre-owned, shops such as Game, Gamestation and CEX. I got my Wii from CEX and it works great
Make sure you have an HD-ready TV and HDMI cable to enjoy all the sexy HD-ness!!
http://www.youtube.com/watch?v=2asf8qHVqKM <-- comparison of graphics between Xbox 360 version and PS3 version of RE5.
RE5 is VERY similar graphics-wise on both systems, both have same features so it doesn't really matter which version you get. I recommend you buy RE5: Gold Edition which has more online features (Versus), modes (The Mercenaries Reunion), costume packs and two exclusive story chapters (Lost in Nightmares and Desperate Escape). If you buy the regular version you CAN buy this stuff on XBLA/PS Store as a downloadable add-on, I find that it's cheaper to buy Gold (it's about £15 now preowned) as it's all on the disc already. No download codes = no content lost to previous owner!
Hope this helps you out, it's really all about which console YOU prefer and what works best for you, so try and have a go with both, think about what features you'd prefer and don't listen to any biased fanboy rants

If you need more help just ask!! If you do get a PS3 in the end, add me on PSN!