A box with guts?
Well that pretty much narrows it down.
I can send a few boxes with guts for fee.
I use Sonar also. But are you looking for a Laptop again?
Or just a desktop?
Either way, go for something at least with a Dual Core 2. Make sure it says "2" after the Core. And at least 2 GB ram.
If you stay close to that all the other features should be up to snuff.
If you are going to go with a Laptop you should know before hand that Sonar isn't friendly to their onboard sound cards. There is a work around because I use my Laptop as my recording DAW as well as almost everything else. But it's a mute point if that is not your direction.
I just heard of an awesome deal at Best Buy that went fast.
But if you monitor
www.dealnews.com you can find out if anybody is having any specials. If you register they can send you emails on just what you are looking for as they bargains come out.
I use them to tell me when Dell is offering discounts using coupon codes because Dell wont tell about them if you ask when your ordering something.
Good Luck, What ever you get should be enough to Handle Sonar.