I just installed the XP-120 on my K8N-E Deluxe last night 🙂 Awesome heatsink, dropped temps by 3 degrees celsius at idle right off the bat. Once Arctic silver settles in, should be an even better drop.
I almost got the Neo2, until I read that it had issues with this heatsink, so I decided to switch boards.
It's a monster though, takes up a lot of space. And once you install the 120mm fan on it, you can barely see your motherboard anymore 😛 Nothing like a 120mm fan blowing 58cfm at 14dBA for silent cooling.
the SP-97/94 is a very good heatsink too. But it also has compatibility issues.
If you're not going to overclock, I'd go with the Zalman CNPS7000CU. Good cooling, low noise, all copper 😛 Kinda large though. As mentioned, the Silentboost is a good pick too.