Look at this thing, now scope out Logitech’s Speaker Lapdesk N700 and come back to tell us the difference between the two. Not that we’d ever dare question the sanity of having two Speaker Lapdesk SKUs, but you’ve got to admit Logitech hasn’t really differentiated its new N550 — a two-speaker, heat-shielded pad for treating your thighs with more kindness and less calefaction — from its admittedly pricier predecessor. After doing some fine investigative journalism (i.e. reading the press release after the break), we’ve discovered that the N550 is designed for laptops with screens sizes up to 14.1 inches, and it also omits the USB-powered fan of the bigger N700. Good to know. Now if someone can explain to us why Logitech is announcing this game changer a whole three months ahead of its January 2011 release for