Eee PC 901 Hard Drive Size Problems
The Asus Eee PC 901 is a very nice netbook featuring two (!) SSD harddrives. I don't know why Asus has chosen this configuration - probably this was cheaper. Unfortunately the SSD "feature" is also its biggest problem. The two SSD drives have 4 GB and 8 GB. And the Windows XP system drive C: is the smaller 4 GB drive which means that you are going to run out of hard drive space as soon as you need to install a bigger application like Microsoft Office 2007 (I have not tested Microsoft Office 2010). This will happen although you chose to install the programs on drive D: which is strongly recommended!
I expect that you are an experienced XP user if you want to proceed here. I know that you sometimes get the recommendation to backup although this is not really required but in this case I strongly recommend to do a backup (Acronis True Image, Norton Ghost, etc.) because you will run out of disk space during the Office 2007 SP2 update and you will have 0 bytes free on your C: drive which can make Windows XP run into unpredictable problems!
Microsoft Office 2007 Installation
The initial installation of Office 2007 is just where the problems start. First of all you need to get rid of all the Eee PC software you don't need. I removed as many programs as I could including all that I did not need, e.g. the preinstalled StarOffice. It is an older version anyway and I would have replaced it with the latest OpenOffice if I wanted to use a free office suite. But I wanted to have Microsoft Office because this is what I use at my company and I am used to it. So I freed up as much space as I could and the initial installation of MS Office succeeded without problems. make sure that you install only the Microsoft Office components that you really need. You are short on disks space!
Microsoft Office 2007 Service Pack 2 (SP2) = Out of Disk Space
In the meantime Microsoft has released Service Pack 2 (SP2) of MS Office 2007 including improvements and security fixes that have to be installed. Although you can download Office 2007 from the official Microsoft site www.getmicrosoftoffice.com, unfortunately you cannot get it with Service Pack 2 already integrated. When doing the SP2 update through Windows/Microsoft update it looks like Service Pack 1 (SP1) is installed first and then SP2 is installed (at least in my case). But you can also download the full Service Pack 2 (SP2) and install it immediately after Office 2007 installation. This is what I recommend. But turn off your network connection to prevent Win XP from automatically downloading the Office updates prior to Office 2007 installation and do not turn it on until you have finished SP2 installation. I recommend to have a second PC to be able to look for troubleshooting on the Internet and download utilities during installation.
Unfortunately you will see that SP2 will fill up your harddrive before finishing installation. And this also happens with the standalone SP2 installer. The problem is that the SP2 installer will have to unpack files first and then starts installing those files which requires much more than 1 GB of free disk space on your C: drive. You don't have that space on your EeePC and therefore your C: drive will become full and the SP2 installation will fail. The annoying thing is that this will also leave installer files on your C: drive and you will have no space or much less space than you had before starting the SP2 installation. This behavior does not speak in favor of Microsoft. Restarting Windows does not free up the space either.
So I first tried to change my TEMP system variables in Windows XP to point to D:\TEMP instead of my user profile on C: and to make the installer unpack the install files there this way but this did not solve the problem completely, I still could not complete the install process. Finally I discovered those tips in the EeeUser Forum describing how to clean up space on your C: drive in Windows XP which you should only apply if you have the experience and understand what you are doing exactly and have backed up your Eee PC. After having run the Windows Installer CleanUp Utility to remove orphaned installer files I got a lot more free disk space. That way I could finally install the Microsoft Office 2007 with Service Pack 2 (SP2) on the Asus Eee PC.
Hope this helps!