可幫忙升級Acer Aspire SA80(晶片組為 SiS 661GX + SiS 964L)？

其基本資料如下：
A choice of powerful Intel® processor -- Pentium® 4, Celeron® or Celeron® D offers robust operation and timely execution
Integrated Intel® Extreme Graphics technology serves up convincing digital graphics without the need for an expensive video card
Built-in Realtek ALC655 audio plays in 16-bit stereo and supports surround sound for lifelike movies, games, music and more
Multiple optical drive options give you a variety of means to create multimedia content utilising DVD and CD media

128 MB of dual-channel DDR266 RAM can be upgraded to 2 GB for extreme memory performance
SiS 661GX + SiS 964L
Extra 5.25" and 3.5" drive bays as well as three PCI 2.2 (5V) slots provide you with the option of adding your own disc drives or expansion cards


目前機器內的ddr ram是 256mb
CPU是 intel celeron D 346


我打算買ddr 400 512mb x 2
但CPU我不知道要買哪一顆才好
因為晶片組支援cpu只有寫A choice of powerful Intel® processor -- Pentium® 4, Celeron® or Celeron® D offers robust operation and timely execution

小弟不才對intel cpu不算很瞭解，很怕買錯
請問我現在該買哪一個顆是符合 SiS 661GX 所支援中最快的CPU?