I hope you have fast internet or a good book to read because the client is pretty big. At 1.64GB it could take a while, perhaps a dungeon raid or two.
Here are the minimum system requirements for the beta:
Windows XP SP3/Vista SP1/Windows 7
2.2 Ghz Pentium IV or equivalent AMD Athlon processor
1 GB system RAM/1.5 GB for Vista and Windows 7
128 MB NVidia GeForce 6600 GT/ATI Radeon 9800 PRO video card
1024×768 minimum display resolution
4 GB free hard space (Beta)