Generally, the Pentium class processors are almost always faster across the board.  You don't mention what clock speed each machine runs at, but I'm guessing the Pentium II is going to eek out a bit more performance, either way.  You also don't mention how much memory the Pentium machine is using but if its an equivilent amount to the Celeron machine, I'd just have her start that databases on the Pentium.  Good luck!

The Dell L433c (433 MHz Celeron) would be slower than the Dell XPS T450 (450 MHz). I would add more memory to the XPS maximum is 768Mb, and turn off any programs that are starting up automatically.

Thank you.  I appreciate the help!