PLEASE!!! What Audio Interface is guaranteed to work with Windows7 and Sonar X1 !!!

I'm sure you'll get lots of opinions. The Roland interfaces seem to have good stable ASIO drivers that work well with Sonar, which seems fitting since Roland owns Cakewalk. I don't have a laptop, but with my desktop computer (Windows 7 x64 Intel i7) I have used a low-end Cakewalk UA-1G interface and more recently upgraded to a Roland Octa-Capture, using 64-bit drivers. Sonar X1 with the Octa-Capture WDM drivers are fairly crashy, but ASIO works great.

RME Babyface might work for you.  It has two mic pre's.

budget?

Highly recommending the RME Babyface ;)

Lance

I have a MOTU UltraLite mk3, and it works with Windows7 64bit.
My experience is that USB 2.0 is quite reliable. The question is (other than the number of channels), if you need super-low latency, i.e. are you going to listen to the audio signal you are recording AND have the signal processed in you PC?

I love my MOTU for its flexible mixing software / hardware that allows you to run several mixes in parallel inside the interface (like a mixer with multiple sub-groups with EQ, compressors and reverb). Since the hardware of the interface does all this mixing and processing internally, low round-trip (send data to the computer and back) latency is not required. However, all this is controlled by a separate piece of software, not by Sonar.

Some people use a workflow that requires low round-trip latency. I find it good enough to hear my voice while recording without the final effects. (Note that playing back other tracks is never a problem because Sonar automatically compensates for the latency of previously recorded tracks.)
Some effects introduce quite some latency. So, no matter how good your interface and your drivers are, you will never be able to use them live. This is true for some convolution reverbs. However, I can use the distortion effects of Guitar Rig with my interface without any noticible delay.

Wilko

you cannot rely on customer reviews from amazon.  my list is based on how much trouble or how little trouble units I've helped people on the forums with over the years.  the ones on the list have been the least trouble, the ones with the most trouble are not on the list. 

No one will be able to guarantee you 100% accuracy that any given soundcard will work on your system.  we can only give you recommendations based on what we know.

I also have an ultralite MK3 on win7x64 and it works 100% fine on my system.

I've successfully used an E-MU 0404 USB interface on both a laptop and a tower system on Windows XP, Vista, and 7. There were occasional glitches when using the Beta drivers on Windows 7 but nothing major.

While on XP I used Sonar 7 and 8. On Vista I used 8 and 8.5. On Windows 7 I've used X1.

http://www.amazon.com/Emu-E-MU-0404-USB-2-0/dp/B000IXNE3E/ref=cm_cr_pr_product_top

I've recently bought a new interface which has worked perfectly with Sonar X1 and Windows 7 - the Echo Audio Gina3G - but that's a PCI card and so won't work with a laptop.

Hope this helps.

Cheers,
Terry.

Audio Interfaces may or may not work good depending on which computer you have.
Not all computers are made to work with a professional sounding audio interface.
So I do not know about that either with your computer, but usually there are test that can be performed given at the link above to know what your computer is doing, and how to tweak it to record music in a DAW system.