Full specs can be found here:-http://www.pny-europe.com/data/sitedynamic/Image/MODULE_DIMM_PC26400-800.pdf
Same price as the Kingston value ram (CL6), however this PNY ram is CL5 so should be marginally better. (either overclock further, or run at stock speed with tighter timings)
This is the cheapest 1gb 800mhz CL5 ddr2 modules I can find at the moment, which is a shame given they were less than half this price 15 months ago!
Don't forget ddr2 performs slightly better in pairs, so 2x1gb will give more bandwidth than 1x2gb. (and at £33.98 for the pair it's also cheaper than the equivalent 2gb module)
Oh, and there is ofcourse 0.5% quidco cashback if you care about the 8p =)