Regarding the USB-calculation: 500mA is the maximum load it can drive (or is it 300mA only? - I think some devices are only specified for 300mA current), so unless external systems are driven directly from USB this does not really count.
If you need LAN for the pandora, then a simple USB-adapter should work just fine (not sure if the one for Wii would do
.
If pandora is closed, then the build-in display should not use much, so power usage should be minimal.
I have also looked at several other solutions, but they all have the disadvantage that they either need to boot from an external device or do not have a display (which is sometimes needed for a sever), have build-in proprietary software (eg. iPod touch - unless jailbreaked
and it has only 64MB of main memory). The beagle-board is quite nice, but it lacks keyboard and display etc., and with all the other things required it might not even be much cheaper than a pandora.
The fit-PC2 is only $245, but that is without WLAN and Harddisk. With Harddisk this is more like $350. RAM is soldered directly to the board, so no upgrade is possible (sounds familiar, eh?). Power consumption is said to be between 6 and 8W, but as this does seem to apply to the diskless versions also, we might assume it is more for the with-disk version (eg. 10-12W). What is most annoying for me is the display driver issue 'cause I prefer open source solutions (ymmv).
Source of information:
http://fit-pc2.com/wiki/index.php?title=Main_Page
With WLAN we have 54MBit/s which should be sufficient for smaller home servers (and who has 50+MBit/s at home?), and if your website is mainly for static pages, serving some files, then 256MB main memory and 32GB SDHC-card should be more than sufficient. For large data-handling DB-based applications (unless DB fits into RAM) Pandora might not be the right choice and you presumably want to use an externally hosted (with 100MBit or even GBit access) server which should be available for a few bucks per month.
For me the pandora seems to be ideal for a little low-power web-, email-, print- and dns-server. Mind you, these are all services that are mainly based on file-i/o, so your only concern should be to get fast SDHC-cards or optimize your cache-settings for this. And if I have to shell out 300+ bucks no matter what solution, I'd prefer to use a pandora ;-)
Just my two cents anyway (0,02 Euro).
Holger