Well, it's easy for people in the IT industry to moan and groan about it. But you have to remember, we're all knowledgable. You and I know it's a five minutes job to install Firefox. We probably also know that Dell image all these PCs, and customer software options may be entirely automated, based on what the customer ticks (so Dell Staff don't do anything at all to install it once they've added it to the software database!).
But so what? - why do you work in the the IT industry? Because you have skills and knowledge you can sell for a price. That's why you are worth more than the legal minimum wage - your employement comes with added benefits or value. Dell are just doing the same thing. The fact that there is more knowledge involved than effort doesn't mean to say they can't charge for it.
Would *I* tick that box? - NO! Not on your nelly. But think about this - I ordered some trousers (Pants, if you're American) online the other day and I ticked the box for some buttons for braces (suspenders, if you're American). I paid extra because i'm not a good tailor, and I wanted the buttons attached by someone who was a good tailor. So I paid several quid for buttons and thread that probably costs a few pence, and the expertise of the tailor in installing them. Because I want good trousers and don't want to spend the evening pricking my fingers attempting to do it for myself.
What Dell is doing is not different from that. They're not "mugging" anyone, just offering to do something for them for a price. If you think it's worth it, great. If you don't, go without and do it yourself.