Dell has shit service, have no idea what politik is on about. Outsourcing the majority of their customer service department to places like Bangalore isn't a deed of promoting 'good service'. The good thing about Dell in terms of customer service is the option to extend the range of services you're entitled to (i.e warranties, type of warranties etc.). When it comes to honouring warranties, that's a mixed bag.
As for screen quality, Dell's high range has 'UltraSharp' and 'TruLife'. TruLife's screen quality is pretty much on par with what Acer offers on their standard 14" and 15.4" widescreen range.
As for reputation, they're both pretty reputable. It's not like you're comparing a generic brand to some huge corporation, so let's move on from that issue.