My experience with Rigol and GW Instek support contradicts that of sirket.
Rigol: Horrible support, usually useless answers
I bought online on eBay, and apparently Rigol hates customers who bought online and not via an official distributor with inflated prices. Every time I contact Rigol support I have to run through some Q&A ritual, just to be told at the end they can't help me. Whatever I do, I always end up at the same support person, and I really tried hard to find someone more helpful. Very annoying is also Rigol's habit of declaring models as obsolete when they no longer want to maintain the PC software. "obsolescence" is at least their standard explanation for lack of Windows 7 software for some models. See below regarding Linux software.
GW Instek: Acceptable support
Here I bought via an official distributor, since distributor and Internet prices were almost the same. Ironically, GW Instek support never cared about where I bought. Owing a GW Instek oscilloscope was good enough for them to help me. With their support I always have the feeling they at least honestly try to find an answer. Not always successful, but they try. A few times my requests ended up at the wrong person, but a quick reminder fixed that.
Similar with using them under Linux:
Rigol: A mess to get it working under Linux.
The usbtmc kernel driver doesn't work for me. It always fails already when trying to open the device. The Agilent kernel driver doesn't work, because it uses old internal kernel interfaces no longer supported. The openmoko libusb driver? Well, after I used it as a model to write my very own driver, I have a libusb driver working 9 out of 10 times. Sometimes the instrument's USB port locks up, requiring to cycle power.
GW Instek: http://code.google.com/p/gds2000tools/
It takes some fiddling to get gds2000tools installed, but then it does its job. Sometimes I have to fiddle with some of the scripts, because they are apparently written for another oscilloscope mode. But overall, it just works.