This can get you into trouble. The board SHOULD support that processor. But you have to remember, Dell, especially the more inexpensive models, are pretty much built with the minimum components required to run the hardware that is in them, and that includes the motherboard as well. To save money, that board will be stripped of any performance enhancing features that a retail version of that board would support.
The only people who can tell you if your processor upgrade will work, is Dell. A BIOS update may, or may not be all that board needs to be able to run the processor you are thinking about.
To everyone who owns an inspiron 546, you can upgrade to a better CPU, provided it's one that was originally sold by Dell with the computer!!! (i.e. Athlon II x2 250, Athlon II x4 630, or Phenom II x4 945) Make sure to get 95w or less, and the C2 revisions (harder to come by than C3-stepping versions). Have not tested a C3-stepping processor, doubt it would work because they did not come out until after the 546 was discontinued.
Yeah, but I'm no expert. I was just thrilled when my new x2 250 worked perfectly right after install. I bet more athlon/phenom ii cpus would work with this mobo, but who has the cash to test all of them?