read this
Disclaimer : Personally have not used it
The Turion is basically a lower-power version of existing Athlon 64 technology, with all the standard features such as a 90-nanometer core, integrated memory controller, HyperTransport bus, 512K or 1MB of L2 cache, and newer core features like SSE3.
This is an important move since Intel does not have a mobile EM64T processor -- indeed, its popular Pentium M and Celeron M parts are based on the old Pentium III architecture. And with the deletion of the Pentium 4 NetBurst models from Intel's mobile lineup, it may be awhile before we see either EM64T or Hyper-Threading in an Intel-based laptop.
So while Intel's Centrino platform arguably offers the best combination of power savings and performance today, the company has left itself open to technological innovations by AMD tomorrow. The Turion 64 provides comparable performance to a similarly clocked Pentium M, but its architecture translates into greater scalability in the future.
Obviously, the current real-world need for 64-bit mobile computing is even smaller than that for 64-bit desktops, but AMD is primarily marketing the Turion 64 as a 32-bit powerhouse that includes all the cutting-edge features, such as enhanced virus protection and power-saving modes (allowing the firm to retire its 62-watt Mobile Athlon 64 in favor of 25- and 35-watt Turion models). The "ready for 64-bit migration" label is the carrot that seals the deal, offering enhanced longevity to a mobile computing market that has enjoyed very little.
Disclaimer : Personally have not used it