Toshiba Notebook Satellite A135-S2326 (P/N PSAD6U-01800D), currently Cel M520 (T2060 - SL9VX) 1.6GHz, RAM maxed at 2G. Machine is slow with Vista, no XP Drivers available. Recommendations for compatible upgrade CPU?
Found your cpu specs. It may be a socket 478 micro-FCPGA. Starmicro has the t2450 running at 2.0 ghtz for $80 oem. A 25% performance boost. The cpu I listed is a dual core pentium mobile 533 fsb; your cpu is apparantly a single core, so you would notice the difference. But if you want to be sure, I'd go to Toshiba's website and look for online tech support. I used hp's online support, and the tech was most helpful, and it was free.
I know this is old, but I was searching for similar information previously, and wanted to add this for anyone else who may be searching in the future. Also, it may be useful to add that I was able to get the T2450 for $20, used though.
As a side note (searching for this information led me to this post): It is the best processor that is compatible with the Sony Viao VGN-N220E which comes stock with the T2060 and 1GB of memory. The memory can be expanded to a maximum of 2GB, and with both upgrades combined, you can have an amazing performance gain for much less than $50 if buying used.
Also, for anyone wondering, the B or W letter at the end of the VGN-N220E model number is just a reference to the color of the actual laptop. It took a while for me to find this information, and I thought I might as well add it into this for future reference for anyone interested.