No to the H50/H70. They are junk for price/performance.
Larkooler is junk as well, I think it is just a rebranded Thermaltake Bigwater kit from the looks. (Also, of which is junk)
Koolance makes decent blocks, as does EK. Swiftech and DangerDen are also other major players in the watercooling market.
Please do yourself a favor and read up on a lot of information:http://www.overclock.net/water-cooling/226970-water-cooling-essential-threads.html
Also read the stickies at the top of the Overclocking forum page; many of these links are provided there as well.