Fogbound,
You cannot complain about the price when you get a Centrino Chipset and a Pentium M along with a DVD/CD-RW Combo Drive.
The RAM your new T5135 uses is:
PC2100 DDR 266 SDRAM SO-DIMM
There is a second DIMM Slot so you can add RAM to the notebook. A second 256Mb stick of PC-2100 would do a world of good to boost the performance of that machine for you.
No need to have more than a total of 512Mb. That is the sweet spot for WinXP.
Enjoy your new notebook,
Richard