Assuming that money is relatively no object, ie under $1200, what would be the best netbook to buy at the 9 inch screen size. Keyboard, battery, Vista (home prem or business) capable and hard drive size are important.
I assume you are looking at ASUS Eee PC 1000H, MSI Wind, IdeaPad S10, HP 2133, Inspiron Mini 9, and Acer ONE. Of those, I like the S10, even though the MSI and HP offer more memory (1GB and 2GB respectively) Looks like, according to your "requirements" the HP is your best bet.
If you are willing to bump in screen size, the ThinkPad X61 is a good one. If you like a LED screen, then there's the X200, but it's more than $1200.