You should create the partition from scratch in the Windows Vista/7 installer. The alignment settings are not exposed in a GUI anywhere AFAIK, and creating the partition in the installer will use the default value. As mentioned previously, the default alignment value in XP is terrible for SSDs, but probably good enough for them in Vista/Win7.
If you want to manually set it to an optimal value, you have to boot to a command prompt, use the diskpart utility to create the partition, and then install windows to that existing partition.