ESX to Hyper-V -
So you have your ESX or Vmware Server set up and you decided you want to test out Hyper-V or Microsoft Virtual Server. You find that you really don't want to recreate your test virtual machines. Well - how about instead just convert them over? Sure would be great if there was tool for that?
Convert your VMDK files to VHD
http://vmtoolkit.com/files/folders/converters/entry8.aspx

Well, now you decided that you didn't correctly size the disks on your newly created vhd, hmm, I know in ESX if I use the enterprise converter I could resize a disk, but how would I do that on my vhd file?
http://vmtoolkit.com/files/folders/converters/entry87.aspx

I haven't used the aforementioned, but that doesn't mean it isn't a great tool for you to try. If you've found this post useful or would like to comment on it, feel free to post a follow up comment.