- giving the "-usbdevice tablet" to kvm will avoid you from needing to click into the kvm window.
- using VNC to access the Windows VM is neat. This is achieved by adding "-vnc 127.0.0.1:1 -daemonize" to the kvm command line. Handy when you have windows running long updates. You can simply close the VNC and let it chug along.
- typing "sendkey ctrl-alt-delete" into the monitor console (you get to it by pressing ctrl-alt-2 and back to gui by pressing ctrl-alt-1) [and, FWIW, using "F8" vnc popup, too] is a bit cumbersome. Therefore, since I'm going to use it alone, I'll redirect the console by "-monitor tcp:127.0.0.1:31337,server,nowait". Then I can create a shell script "send-ctrl-alt-del" that will contain the simple netcat call: "echo 'sendkey ctrl-alt-delete' | nc localhost 31337" - and then bind this to some key combo in fluxbox.
- do not be afraid to undershoot with disk space for win7. You can create a sparse 1gb file by doing "dd if=/dev/zero of=1gb.img bs=1024 count=1 seek=1048576" and then by appending this file to the image "cat 1gb.img >>win7.img". After that in the disk administration you can simply grow the volume by 1Gb.
- for accessing the files on host, if you do not have anything SMB-talking, you can get away with using the SSHFS. http://dokan-dev.net/en/ is precisely that. It allows userland filesystems as windows, and includes the SSHFS filesystem. It's a bit rough on edges, but works. Assuming you are using the kvm built-in networking, you will always connect to 10.0.2.2.
If this is your personal client machine, no need to keep ssh open to the world - so edit the /etc/ssh/sshd_config and put "ListenAddress 127.0.0.1" there. Do not forget to restart sshd afterwards.
When you boot up your Windows you can connect the drives back to the host. Beware to turn off the cache - else the changes would not be reflected immediately and such a setup becomes tough to work with.
Hopefully this will be useful to you.