Screen: Both with wvga 800X480 resolution, Q5W's screen is bigger though...

N810 has a keyboard while Q5W doesn't

N810 has GPS but reviews show it doesn't get any signal until 3-4 min waiting from a cold boot, so I guess that's not useful. On the other hand, the GPS cradle of Q5W works really well.

N810 has storage extension with the SDHC slot but Q5W only has 40GB hard drive without extension.

Q5W has USB port and TV output while N810 doesn't...

Which one should I go for?

Cowon is definitely an interesting device. For me the lack of keyboard kills it, and the price is higher, especially if you start adding things like the GPS. The Win CE OS has its pluses and minuses, but I consider it overall less appealing than the open Linux platform of the n810.

The advantages are storage, screen size and things like TV out. Disadvantages are that the storage is not solid-state, meaning it's more likely to fail, and of course it's overall bigger and heavier making it less pocket-friendly. The n810 by comparison fits nicely in the hand or pocket.

I think if you're more inclined to a PMP with web browsing capabilities, the Cowon is the device to get. If you're looking for something that is more productivity oriented and focused on things like skype, chat, blogging, email, etc. the n810 is the better choice.

It also appears to support a2dp which means if you travel with a bag, you can just toss the unit in there and have a tiny receiver for your listening pleasure (one that I used quite successfully was this: http://www.dealextreme.com/details.dx/sku.8422 ) Tomtom on WM5 has been wonderful.

I'm still partial to the n810 due to it's pocketable size and potential. By the sounds of it, the n810 device programme has brought a whole lots of developers that do really interesting stuff into the fold.

Still... what do /you/ want to do with these units? Thanks for bringing the Cowon to my attention, it's a really interesting product.