I have a Dell inspiron 1525. Due to my GPS antenna
causing Win 7 32 bits to crash, I partitionned my hard drive in three. C---Win7, D---Win XP and E---data, charts etc.. I dual boot and choose drive D when I sail. My nav softwares are on D, including Maxsea.
You could try this. Another advantage of this is if you get a virus or other cyber crap while on Win 7, you can just format C and all your nav software are still working OK sitting on the D drive. It also have the advantage to keep to a minimum the software/services running and slowing down your PC while sailing since you could only install what you need for sailing on the D drive and install all your other software on C--Win 7.
Works great for me.