I took the plunge & installed SL 10.6 on a Dell 1012 last Summer - Recently got a great deal on a brand new Dell 1018 so planning an install of SL on it. New WiFi card on order, upgraded to 2Gb RAM.
Major differences I've noted thus far: 1012 =3 USB ports - 1018 =2 USB ports, NO mic input on 1018, 1012 =2 speakers - 1018 =only one speaker. 1012 =DDR2 RAM - 1018 =DDR3 RAM. 1012 seems to be the more "up-scale" of the two . . .
However, I like the trackpad & actual mouse buttons better on 1018 than the integrated system on the 1012. I know what some are thinking BUT the trackpads are not inter-changable nor is the top case - external they look the same BUT underneath are completely different at least between my 1012 and 1018. I can live without a 3rd USB and a Mic input in exchange for a trackpad I can live with!
A note of interest with my 1012, (I am guessing will be same with 1018) VLC player does not show FLV movies (I know the hardware acceleration is issue) BUT for some reason a free version of a player called Wimpy FLV DOES allow me to watch FLV videos! I've watched a 17mb music video & 130mb Star Trek TOS episode both are .FLV format.
As for graphics I've found the old version of QuickTime 7.6.6 works for JPEG viewing (haven't tried beyond 2mb size) AND QuickTime 7.6.6 also allowed me to watch a 150mb .MOV Star Trek TOS episode.