Not sure if you're talking about the free trial or the real game, as you say Escape to Norrath (the free trial), but said paid for it, which would imply the real game.
I have no clue about the trial, but as far as the real game, you might look at the info on the following link, and use it's downloader to download the game:
http://help.station.sony.com/cgi-bin/soe.cfg/php/enduser/std_adp.php?p_faqid=1812
Thanks to missjackie for excellent link in a recent post
Also, not sure if it's an issue on Win7 or not, but on Vista, the game often won't work correctly when installed to C:\Program Files (x86)\. You may also want to look into, although probably fairly unlikely, redownloading DirectX. Again this is pretty unlikely, unless you've installed something that has modified what came with Win7.
Hope this helps some,
Yther Ore.