They will both happily run the FULL Ubuntu or Mint … but here’s what I’d install …
On the netbook … PeppermintOS (Two) … I have this on my Acer Aspire One (8GB SSD, 1.5GB RAM, N270 CPU) and it suits the netbook perfectly.
It’s based on Ubuntu 11.04 so has access to the Ubuntu software repositories (all the latest software) … I must point out that it is a “cloud” type distribution, so most of the default applications are internet based (google docs etc.) but there’s nothing to stop you installing things like LibreOffice locally (which installs with just a few mause clicks from the Synaptic package manager) … it is also VERY quick, and as your CPU is basically the same as mine (single core, dual thread), I would expect similar performance 
There’s a tutorial for installing PeppermintOS (Two) on an Acer Aspire One here:
http://linuxforums.org.uk/index.php?topic=9782.0
Which should all apply to your netbook, with maybe the exception of the hardware fixes (stage 10 and 11).
As for the desktop … I’d go for Ubuntu or Mint … but I’d probably wait till the end of April for the the 12.04 to be released, 12.04 being an LTS release (LTS + Long Term Support) … then if you don’t like the default desktop (Unity) you can always change it to Gnome3 or gnome-session-fallback (which is more like the older Gnome2.x desktop.
as for requirements, surfing ,emails, photos, music, some downloads, watching Iplayer - the latter 3 mainly for PC but while away net also. i think Ubuntu is good for these? Also would you recommend 11.04 as more reliable than 11.10?
Or you could just go with PeppermintOS on both … though again I’d expect there to be a new release of Peppermint shortly after Ubuntu 12.04 is released, based in it rather than 11.04.
as for requirements, surfing ,emails, photos, music, some downloads, watching Iplayer - the latter 3 mainly for PC but while away net also. i think Ubuntu is good for these?
Any Linux distribution will be fine for the uses you list.
Also would you recommend 11.04 as more reliable than 11.10?
Not really … although if you definitely want the older Gnome2 desktop, then 11.04 was the last version to have that.
Distributions I use
Desktop PC = Ubuntu 11.10 (with the Gnome 3 desktop … I don’t like the default Unity desktop)
Netbook = PeppermintOS (Two) … which though it takes a little tweaking such as installing some “local” software, I absolutely love … that much I’m in two minds whether to stick it on my desktop.
As BkS says … Skype is in the default software repositories for Ubuntu, Mint, and PeppermintOS … and is an easy install.
See the Peppermint tutorial, it’s in that 