DDR2 2GB 1066 MHz U-DIMM *2
http://www.modreactor.com/english/Reviews/DDR2-DDR3-Memory-Roundup-Corsair-Patriot-GeIL-Elixir/Page-15.html

Pros:
 * High frequency
 * Very cheap
 * Modules sold separately, not in kits
Cons:
 * At the current price and performance, the timings (6-6-6) and lack of radiators are somewhat of disadvantage, not huge but disadvantage nevertheless

“As you can probably tell, we liked Nanya Elixir DDR2 1066MHz very much. Modules are cheap, stable and thanks to their volume and high frequency they dash swell performance in games.”

DDR3 2GB 1600 MHz U-DIMM *3
http://www.modreactor.com/english/Reviews/DDR2-DDR3-Memory-Roundup-Corsair-Patriot-GeIL-Elixir/Page-16.html
Conclusion
Pros:
 * High frequency
 * Very low price
 * Coolradiators, the memory looks awesome in clear cases (or windowed for that matter)
 * Modules sold separately, not in kits

Cons:
 * At the current price and performance, the timings (9-9-9) and low overclock potential are somewhat of disadvantage, not huge but disadvantage nevertheless

DDR3 2GB 1600MHz U-DIMM *3
http://www.rwlabs.com/article.php?id=182

“ Great performance with a great price tag...the Nanya Elixir
kit solely because you can easily run it at 1780MHz.“