I would also consider the value loss (both the financial value and the photographic value) of the camera.
Certainly, you don't buy a camera as an investment object, but you would most likely like it to keep some value and be a usable photographic instrument for some time to come. To be quite clear ... the camera does not lose its 'value' as a camera from you using it. It will continue to make great images (assuming that is what you buy it for in the first place), but technological advancement will raise the standards and mayb e your expectations.
In early 2003, I bought a G2 for about 900$ ... at this time maybe not the apex of technology, but as good as you could get a camera below 1000$.
About 2 years later, I got a 20D in early 2005 for about 1200$ ... a bit more expensive, but not substantially more.
Now when I look at the value (both the financial value and the photographic value) 2 years after the purchase ... the G2 was quite outdated by the time I got the 20D. I kept it as a backup, but have since very rarely used it. Resale value? Forget about it.
When I look at my 20D now (also 2 years after buying it, same time when I upgraded from my G2), to be honest, it feels as if I just bought it yesterday. It is certainly in no way outdated, and I will continue to use it for quite some time. To be honest, it's the camera I have wanted all my life (had a NOINK SLR, but seldom used it because getting images processed was a PITA). Sure, a 5D or 1DMKIII would be nice to have, but this is nothing compared to the longing glances I had at about any dSLR with a big sensor when I was still using my G2.
Since getting the 20D, I have been adding some good lenses to it and if I decided I want to sell it now, I would be confident of getting maybe half the money I paid for it back.
So ... morale of the story?
I personally found the compact camera lacking in some respects that were vital for me, and was very eager to make the upgrade when dSLRs became available at 'normal' prices (launch of 300D). If there is a possibility that photography might be more than 'just another hobby' for you and you don't want to take the camera wherever you go, then I'd suggest to get the dSLR.
Best regards,
Andy