I upgraded to Windows 7 early this week. Since I purchased this laptop (HP dv4) I have been running Vista. The entire Vista experience was disappointing (at best). We also ran Vista on two other laptops in our home. The units were sluggish, experienced frequent crashes, and shut-downs, while not the biggest issue, were a challenge. At work, we never made the move to Vista so I still run XP.
The upgrade experience was very smooth on all three units. It took about 3 to 4 hours each. I purchased the 3-pack upgrade from Amazon at a great introductory price. It came with both a 32 bit and 64 bit version of the upgrade.
So far I am one very happy guy. I still pan to buy a Mac early next year! I am anxious to update at work .. well, maybe not. That will have to be a wipe and install. Maybe I should buy a new laptop:).