It's kind of interesting. My 5100 has the ATI Radeon 7500 Mobility video and a 2.8Ghz P4... Other than those two seemingly minor specs, the machines are the same.
The 5150 machine I used had a Geforce card. Most of the major problems I had were graphical or mouse pad related. I disabled the touchpad and suggested the a friend of the friend that she try using an external mouse for now. I tried synaptics, but the acceleration was either too fast or slow and ran out of time to tinker with it. It was difficult to logout of KDE gui at first as menu kept opening and closing before I could click on the option. Nvidia was installed, I suppose that is the culprit. Also it will not powerdown. I did not have time to build a new kernel. I wish I could have solved this quickly and Boot time was pretty horrible. No offense: but I personally have a hard time with Dell. I don't have a week to configure everything only a couple hours. IBM is still best (if I could afford one) followed by my cheapo HP Pavilion with blue disco lights. (on a side note I must add that Slackware 10 installed easier on my other laptop an HP and even had touchpad working. Only powerdown (which did work with SuSE 9.1) did not work. It also boots twice as fast and was easier to configure: sound and DVD worked out-of-box-)- strange you would think it would be the other way around-(easier to upgrade too with swaret) Slackware 10 had poor hardware detection on my home PC though so I am sticking with SuSE here and for client installs who like to hear the word "Novell" etc)