If you need some memory, now is the time to buy. German alternate has dropped the price of OCZ's DIMM 4 GB DDR2-800 Kit (OCZ2P8004GK, XTC Platinum) to an insanely low $59. You get 4GB of DDR800 with 5-4-4-15 timings, but believe me, 4GB makes a difference once you run out of your 2GB memory. Timings are not that great, but 4GB still beats 2GB, at least in most of the cases.
OCZ 4GB kit can be ordered here, but at press time it looks that you might have to wait three to five days before they ship it to you; while you will wait up to 48 hours for the Transcend memory.
If you are just looking for any 4GB memory kit and want to spend below €50 you can buy a Transcend kit here for €46.