Both surf the net and both can serve as media hubs/player/streamer. Both can use a USB keyboard/mouse. Though not for games. Microsoft forbids it and while Sony does permit it, only one game (Unreal Tournament 3) supports it for some godforsaken reason.
The PS3 has an edge if internet usage is desired, as It supports bluetooth for wireless keyboards/mice. Plus, while both have ethernet, the PS3 comes with wifi built in. It's also got 2 USB ports, though with a mouse + Keyboard + controller (they charge off of a USB port) you may still need/want a hub or separate controller charger.
Plus it is still one of the best Blu ray players.
If you want to use the console as a media hub, the PS3 is quite simple to upgrade the HD on, though it does use the more expensive/smaller 2.5" (ie. notebook) drives. The 360 is... not. At least if you don't want to buy a highly overpriced HD from MS.
The 360 requires a separate adapter for wifi that is quite expensive ($100 list!) and occupies the only USB port, though AFAIK there's no reason you can't use a USB hub with it. There doesn't seem to be any wireless keyboards/mice for it, though there is a texting keypad that you can put on your controler. Sony has recently introduced a similar item.
All this having been said.....I've personally got both consoles (I'm sure I'm not the only one), and I find that the built-in WiFi in the PS3 is less stable. It tends to be a weaker signal, and disconnects more often.
The PS3 itself is quieter, and it *can* surf the Internet.....but typing is a pain with the controller....the new keypad will likely help with that. But I find that the PS3 browser gets confuddled by a lot of pages that have scripting etc. on them.....sometimes to the point that the browser crashes my PS3 and results in needing a reboot.
The XBox 360 doesn't browse the Internet at all....unless there's some kind of a mod to do so...which I've never looked for. Microsoft has a bunch of limited pages available in the Live Marketplace....but I can't like, go to Google and search for hockey cards, for instance.
The PS3 tends to have a bigger hard drive, and you can replace it with ordinary laptop hard drives......but the PS3 *needs* that hard drive. You might find that it runs out of room quicker, because most PS3 games require that they save the game content files to your hard drive......so each game could place between 3 and 6 Gigs (or more, like with MGS4) of files onto your hard drive. This is needed because the Blu-Ray drive spins slowly enough that it can't effectively pull game cnotent off the disk quick enough.
The XBox hard drive tends to be more expensive, and a pain to move files from an old hard drive to a new one....but the space lasts longer, since you don't need to load games onto it in order to play them.
The PS3 runs quieter, definitely, but, personally, I find the software garbage compared to the XBox softare (I'm talking about the OS, interface, and applications that run with it). As a media server, I'm very displeased. I've spent hours trying to configure it to stream the MP3's from my PC, but the PS3 finds maybe 5 songs, out of the 300 I've burned from my CD collection. And the support documentation is not very useful for solving the problem. On the other hand, the XBox? As soon as I was able to get it to handshake with my PC, all the songs were there. No problem.
The XBox, in my view, is a better platform for online gaming....the interface is more user-friendly. But I admit that others may differ in their opinion.
I like both units, and I'm getting to like the PS3 more....but it's taken a while, and I still find the 360 to be a more fun overall experience for online gaming. It's way easy to walk into games, find matches, and chat with friends. I just find the PS3 counterintuitive at times, in comparison.
Banshee
Unless there's something wrong with my hearing due to spending so many evenings in my 20's listening to loud music in bars......admittedly the XBox *is* louder.......but it's kind of like comparing the background volume of crickets to the absolute silence of the PS3.
