I would say no. My wife is running a HP Mini Vivienne Tam edition. I tried running photoshop CS3 AND CS4 on it, and edit a raw file. Man it was a painful experience.
I recently bought a HP DM3 ultraportable (see it here http://bit.ly/a3dG5s), its bigger then the Mini, but man its a lot better at editing even RAW files.
Max ram on most netbooks are 2GB. Most ultraportables max out at 4 or 8, that alone makes a big difference. The netbook uses really crappy graphics chips as well. Wheras the ultraportables use actualy discreet graphics. BIG DIFFERENCE.
If you are not going to install photoshop or other similar software, I would suggest you at least get Picasa3 installed on your netbook if you want to do some PP on the photos. The only other limitation will be the disk space. You might run out of disk space pretty soon with today's 18+MP photos.
I'll say yes - especially since you've stated you don't do a lot of post-processing. Intel Atom N280 netbooks have accompanied me on a couple of overseas trips, and I've used them specifically for photo data storage + simple cropping and resizing, color adjustments using the Fastone image reviewer, and it works just fine.
Any sort of intensive pp work though involving Photoshop will be too much for the netbook to handle, unless you're getting one that's equipped with one of those netbooks with dual core CULV processors, which might make the pp experience more bearable IMO.