Canon Pixma iP4000 or Canon Pixma iP5000

As far as I can tell the main difference is that the 5000 has a much higher resolution does the higher res make it worth the extra cost over the 4000? Are there any more features which seperate the 5000 from the 4000 in a significant way? Ive looked and as far as i can tell there isn't muich diference.

In addition to this which one would you recommend and where can I buy either one of these printers? At the moment I’m finding it hard to find these printers especially the 4000. The best price I’ve found for the 5000 is £115 but ideally id like to pay under 100 quid. Thanks for any advice/help provided.

Saw your post on this, and thought id let you know I was about to place my ip5000 up for sale any day.
Its about 6 to 9 months old but in mint condition (not a scratch on it). So much so it look liek its just been taken out of the box.
Anyway if your interested im selling it (boxed as it came) for £95 with a full 2 sets of extra inks.
Collection is ok (im in London) or postage will be about £10.
LMK if ur interested m8 b4 i place it up for grabs.
Cheers.