I removed the /opt/virtualbox and reinstalled and have installed win xp again. In fact this is sent with iexplore in win xp in virtualbox. But I guess I will have difficulties updating xp.
What updating are you trying to do? Have you set up an Internet connection in your Windows installation?
Running Windows in a VM is just the same as running it from a direct installation, in my experience. The main difference has been games up 'til now, because of the lack of proper 3D in the VM, but that is being worked on. I don't do Windows games, so this singular lack doesn't affect me in the least.
If you've got the Guest Additions
installed, the VM window sizing problem should vanish. Speed may still be an issue, but that depends on the amount of RAM you've given your guest OS. On this machine I have 2GB total installed RAM and give half to the VM, with 128MB given to the VM video. It's a bit slower than a normal installation. On my other computer with 4GB total installed RAM, I also give half to the VM, and any speed difference is imperceptible. Some things actually run faster in the VM than they do in a normal, on the metal, installation. That probably has more to do with the actual hardware of the machine in question than anything else.
My only reason to have a VM, with Windows, is to run my scanner that has no Linux drivers available. With the Windows VM I can use the drivers from the CD that came with the scanner, scan what I need to scan, then move the file to a directory shared between the VM and the host OS. On the Linux host I then can do whatever processing I wish with the Linux tools; mostly Gimp. I do have one Windows app for simple photo processing, which I use mostly to view the scans, to verify their correctness, rather than actually process them, although I do occasionally do a little minor touch up with it.
I don't go online from within the Windows VM. If I wanted to install some Windows freeware application, I'd d/l the app from the Linux side, place the installation file in the shared directory then run it in the VM. I installed the Windows Service Packs
this way. This keeps all the internet bad stuff away from Windows, which stays isolated in it's own little sandbox. So long as I keep Windows off of the internet, most of the other security patches and such are not necessary.