Toshiba Silver 15.6" Satellite L455D-S5976 Laptop PC with AMD Sempron Processor & Windows 7 Home Premium
At Walmart for $398.
My son is concerned it wont run Office quickly at all. Is it worth the money?
Also, it can hold up to 8GB. Should he increase?

Should he increase from what? The SCREEN size and OS aren't important - ram and processor speed are. And all things being equal, the apps should run fine.Sorry....
2GB of DDR2 system memory rated at 800MHz and expandable up to 8GB
250GB SATA hard drive, rated at 5400 rpm
I don't know what the processor speed is, but since the system is rated "powerful enough" to ship with Windows 7 you'll be fine.AMD Sempron processor for NOTEBOOK PCs, SI-42
Features 2.1GHz speed, an 800MHz frontside bus, and 512KB L2 cache

Thanks for your advice....Remember that MS Office has been around a long time and was running just fine before Windows 7 and TODAY's processors.It is a good choice. Go for it!
That PC can l run any version of Office.
And it is fast.

Just do not put junk on it. I mean those 'free' trail things that mess with the system and later you have a hard time trying to remove.

One of the first things you do with any new computer is to set up a recovery procedure recommended by Microsoft. But some people turn off the built-in safety net because the local geek SAID it would make the system faster.