I have no particular axe to grind when it comes to laptops, but I am writing this on an Acer Aspire 1800, which I've owned for 2 years. It has 3.2ghz P4 processor and 2gb of RAM. Graphics are 128mb Radeon from ATI.
It was purchased to specifically run high end video editing software and to allow a continuous linear production process from capturing 720 x 576 DV video streams through compression to DVD authoring.
It has performed flawlessly since the day I bought it (hopefully not the kiss of death!). I have experienced Dell, but would generally comment that to get the best "value", you have to purchase whatever they happen to be offering at that moment. Start adding extras and they become very uncompetitive.
Keep asking folks for their experiences and opinions and you'll get closer to an informed choice. Don't rush into it!!