Did this again last week (different car!), I tried to loosen the clips as suggested, but it was far easier just pulling them off completely. I also recommend doing them strut at a time for safety reasons.
This time I was more careful with my screwdriver and didn't scratch the paintwork
Hands were COLD afterwards though.
This time I bought TUV approved aftermarket struts:
http://www.ebay.co.uk/itm/190781818412
They do seem more suitable for the car than the Magnetti Marelli ones that I bought last time (only £2 difference, both 50% cheaper than the gen Volvo price)
It lifts up easily to halfway and then a helpful flick sends it to the top. They are loosening slightly with use, I had to really slam the boot a couple of times at first, so I wonder if they'll soon start going all the way up in one fell swoop. 2 year guarantee on them.
Aesthetically, I prefer the aftermarket all-black ones that came off my car, but that's a matter of taste, and I don't exactly open the boot and think "oh no, not more chrome", but I did used to think "ooh, those black struts are nice", and as they're aftermarket, clearly they apparently didn't last very long!
p/n for comparison is
30803472