There shouldn't be any problem with adding wubildr:
Originally Posted by emongev
Sometimes Ubuntu will update the wubildr (when package grub-pc is updated). I believe that - since Natty - it will search and update all the wubildr files that exist (in the root of all partitions), so should be good.
sudo mount /dev/sda1 /mnt
cp /host/ubuntu/winboot/wubildr /mnt/wubildr
sudo umount /mnt
If the delay is not so long I wouldn't bother. Maybe you just need to defrag C:\ to get a quicker response.
Or partition and install direct - eventually you'll be doing this if you like Ubuntu anyway.