I'm also an Acer fan. Support was excellent when I needed it.
Acer is a brand that always seems to have a model pitched at a 'sweet spot' price when I buy one.
Having said that, I haven't heard any criticism of Dell laptops. Desktops, yes, proprietary hardware makes upgrading difficult, but with laptops that's almost always the case. You can change/add hdd/ram/keyboard and optical drive, but that's it.
Dell's recent stand against Vista is also to their credit. The last Acer I bought was post Vista launch, but came with XP Pro and a Vista update - which I won't be using for a while yet.