Thanks guys.
I've got/on the way the following so far:-
AMD AM2 Athlon 64 4800 EE version
ASUS M2A-VM HDMI motherboard
Crucial 2Gb (2X1Gb) 240-pin DIMM, DDR2 PC2-5300
Seasonic S12-430 PSU
Samsumg Spinpoint 250GB HDD
Samsung SH-S183L/BEBN x18 18x DVD RW
Zalman 135 HTPC case in black
Yet to order
Windows Vista Home Premium
500 GB HDD (seagate/samsung/wd?)