The age old Laptop vs. Desktop debate still alive and well I see

A lot of people seem to be wanting laptops these days... I'm not sure if its an 'image' thing, like IPod's etc. or because everyone in the movies has one or something... but as I see it, it essentially comes down to a couple of factors:
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Size:Laptops (although most should be called desktop replacements these days) are smaller than a standard desktop machine + monitor... If space is at an absolute premium, then the 'desktop replacement' is most probably the preferred choice. Otherwise, because of most of the reasons below, you should get a desktop
Portability:Fairly obvious really, if you require portability, Laptops really are the preferred choice. Having said that, I used to regularly move my machine around (nowhere nearly as often as Mike) to go to LAN's etc. and you will develop a 'system' that enables you to do it fairly painlessly.
Upgradeability:Laptops, usually, cannot be upgraded any further than putting some extra RAM in it, or swapping out the optical drive for a new one (if the laptop has removable bays)... so if you are certain, that your performance requirements are not going to change too drastically over the next 12-24 months, then by all means get a laptop. Otherwise, you are setting yourself up for a painful (read: costly) upgrade when the laptop no longer suits and you need a new one.
Cost:on a price/performance scale, desktops usually beat laptops fairly convincingly... so for the same dollars, a desktop will have superior spec's. Also, do not forget that most, if not all, laptop manufacturer's consider batteries to be a 'consumable'. When the battery craps out, it will usually not be covered by the warranty (or 12 months max) and they are usually not that cheap, if you can still find one, to buy.
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I would advise you to seriously consider each of these points, and figure out what is most important to
you. Everyone is different and has different priorities and needs. Once you are sure which way you need to go, then you can start looking for a machine that fits your requirements.
cheers,
HCP