When it comes to computer resources I've always had this philosiphy that you don't have enough until you have more than enough. That philosiphy worked out fine for me in the desktop days when the cost in space and power consumption were unnoticable. But now with all my machines (save one) being portables, it makes a big difference.
The laptop I use for work is a Dell Precision M6400. I received the machine with 4 gigs of ram and a measley 160 gig hard drive. The machine had empty memory slots and an empty drive slot. So I bumped the ram up to 12 gigs and added a second (500 gig) drive. Adding the RAM solved a performance problem I was having; 4 gigs just wasn't enough for the virtual machines I needed to run and for multiple instances of Visual Studio. But now that I have the RAM the machine runs much hotter. When it comes out of the hibernate state I've got to wait for a 12 gig hibernation file to open. If I put it in standby it won't last a full day before the battery dies. With the extra drive and the RAM together its hard to make this machine last much longer than 20 minutes on battery power. I didn't think I'd ever say this but I don't plan to ever max this machins RAM or storage out in light of the tradeoffs of doing so. I'm going to take the original hard drive out.
The lesson I learned from this is that everything has it's cost, even having more than enough.