Per the Boeing website, the following is the performance for the 3 versions.

747-400
7,260 nautical miles (13,445 km)
0.85 Mach

747-400ER 7,670 nautical miles (14,205 km)
0.855 Mach
in service October 2002

747-400XQLR (7,980 nmi, 14,775 km) 9,190 statute mi
Mach 0.860
in service as early as 2004 if Boeing launches product.
http://www.boeing.com/commercial/747family/sitemap.html

A cool map showing the range comparison between the 400 and 400ER for Singapore is at:
http://www.boeing.com/commercial/747...singapore.html

For New York:
http://www.boeing.com/commercial/747...c_newyork.html

Things to keep in mind, the XQLR is not launched right now since no airline has purchased any. Also, the ER which goes into service in October can fly LAX-SIN nonstop along with NYC-BKK.