The entry level SLR category is designed for two types of people: those who haven't owned an SLR before and are looking at stepping up their photography experience from a digicam and those who already own SLRs (either pros looking for a second backup body or semi-pros looking to upgrade to a more recent entry-level SLR). Entry level DSLRs have large sensors, many times larger than those in the average digicam but smaller than pro SLRs. Out of the gate even the cheapest SLR is going to have great image quality relative to your average or even expensive digicam. You're going to get better high ISO performance, manual assignable manual control wheels, better handling, fully configurable setting, macros and of course interchangeable lenses. Entry DSLRs are very robust and for most users more than adequate. Most people will be best served with an entry-level SLR and an investment in some good lenses.
Owning an SLR is as much about the glass (lenses) you own as it is about the quality of the camera body - don't skimp on your lenses or you'll never understand what the DSLR body is actually capable of. If you plan on buying a lot of lenses than the system you buy into is important because it will determine the lenses you can buy and the bodies available when you upgrade (and you will) in a few years. Unfortunately for the other manufacturers the biggest range of lenses are available for Nikon and Canon cameras so they are the easy choice if you're unsure what DSLR manufacturer to choose. Because entry level SLRs have smaller sensors than their professional full frame sensor counterparts they have what is called a crop factor. You should read more about crop factor but the end result is that a given lens on a entry-level SLR is going have a different effective focal length then the same lens used on a full frame pro DSLR. The crop factor is typically 1.5X meaning that you multiply the focal length by 1.5: the effect is you get less wide angle and more zoom - great for sports photographers.
Snapsort pulls out SLRs into the pro DSLR based on body size, sensor size and a few other pro features, and puts the rest here into entry level.
Recent Entry-level DSLRs by manufacturer
Here is an overview of the manufacturers of entry-level DSLRs, the most popular shown first.
Snapsort has found 2 recent entry-level DSLRs from Canon.
Snapsort has found 2 recent entry-level DSLRs from Nikon.
Snapsort has found 2 recent entry-level DSLRs from Pentax.