You can increase the Turbo slightly on some H55 boards (can't find a link to this) along with a very slight BCKL increase for non-K editions.
http://www.xtremesystems.org/forums/...d.php?t=264192
What is great about SB is you are looking to get a new CPU/MB now is that with a 2500k and cheap P67 board (currently ~100 on entry level MSI and Gigabyte boards) it might be more expensive than an X6 + board but for gamers, the advice amongst most the reviews so far is this is a better option now than a similar AMD setup.
It looks like you can OC higher, the chip runs cooler, uses a lot less power and gets you better performance. Whether this is worth the extra cost over an AMD setup is up to the individual of course, depends on your budget and expectations.