Laptops - RAM vs Disk for performance

In the perfect world I could get everything I want, however budgets for new laptops are low so I normally can get a user a laptop + additional RAM (to at least 4Gb). This has been mostly motivated by Vista's RAM eating abilities - however I have always thought that putting in a faster drive (i.e. not the standard 5400rpm drive) would have a bigger benefit.

What would you put (more RAM or faster disk) in for laptops running Vista/Office AND Win7 or XP/Office (since they are less of a RAM hog)?

Solution 1:

More RAM is the way to go. Running multiple applications, that extra RAM will do a lot more good than a faster HDD which is still physically restricted to it's single spindle.

Once you run of RAM and the OS starts paging to the HDD, your system will crawl irregardless of how fast your HDD is.

Solution 2:

Identify the most common bottleneck (e.g. with perfmon.exe) and base your decision on that.

I would generally choose faster disks since I witness IO bottlenecks more often, especially when machines are loaded with the Corporate Performance Taxes (anti-virus, Landesk, Sanctuary etc)