one of my boxes is running windows xp pro and oddly all of a sudden whenever theres a short "lag spike" id call it, it makes a clicking noise from within the box. like a kind of sound where your cd drive is trying to open but its stuck. that kind of sound. any suggestions?

NIC card acting up in some way? All i can think of is some sort of hw problem like that...

Could be the hdd on its way out.. if it hits an area it cannot read, it will make like a clunking sound.. and you pc will freeze.. its happend to me before... It may not be this, but it may be worth backing up ur hdd.. then try running a surface scan.. Worth a try.

Maxtor have a nice universal HDD diag tool - have a look on www.maxtor.com for 'Powermax'.