I'm currently in possession of a Shuttle SN45G (v1) with Athlon XP2500, 1GB RAM, Radeon 9600 and the usual bits and pieces. I am however thinking of upgrading - not because I'm unhappy with the performance, but because I've "outgrown" the Shuttle - and I'm getting annoyed with having external USB/Firewire drives hanging off it.

The real questions I have are as follows:

1. On a modern system (think Athlon64), how much of a bottle-neck on system performance are hard drives? Is it worth me setting up a striped array for the system (Windows) files?

2. Does it make any sense to invest in a dual Opteron board and, due to budget constraints, simpyl use only one CPU for now, but add one in later? And does normal 64-bit XP (though probably Vista by the time I add a 2nd CPU) come with support for 2 opterons? Or am I better off just going for a single Athlon cpu?

As a general rule, I play the odd game- but nothing too serious -- I'm just keen to get as much life out of my machine as possible; hence the RAID and multiple-CPU questions.