This's what I'd advise (in terms of BEST quality)
I hope you're willing to maybe buy from more than one shop, cause I'll quote from different shops :
Motherboard :
Choose your chipset first.
I'd go with either the P45 or X48.
P45 supports DDR2 - 1066, X48 only via OC'ing.
The ASUS boards are only that popular because of the added sound-card.
You have a sound-card, so it's unneccessary.
Best boards IMO (quality-wise):
DFI, you can get them at
www.landmarkpc.co.za
Board that's current world record holder for best OC (highest FSB on a P45):
Biostar-Tpower
My choice : DFI P45.
CPU :
E8500 is best value for money ATM.
(Upgrade to a 3.5 odd GHz Quad in a year's time when it's supported by games.)
If you're not scared of whipping out another R1000, get a Q9550 now already, they're about R3400 @ pcint.
RAM :
If you're not looking at overclocking too madly, go cheap!
If you go P45 : Get DDR1066
The following sticks are all great :
If you go X48, either overclock and use the DDR1066's or get some of these : DDR800
DDR3??? - not worth it yet.
PSU :
I'd keep the one you have, it's a great PSU and you're gonna waste it if you buy a similar new one.
The following are all great :
HDD :
There's been some complaints against the new Seagate 500GB's. I think the new batches is fine though.
Your own choice, either go 320GB, but I'd go for either the 500GB from
www.pcint.co.za
Graphics :
The Sapphire 4870X2 is fine, BUT :
You'll NEVER need 2GB Video-RAM on 1280x1024
If you plan on keeping the 19", rather go 4870.. It's almost IDENTICAL in performance on resolutions < 1680x1050.
Sell off your 19" and buy a 22" or better, lookey here :
http://www.landmarkpc.co.za/store/samsung-t260-rose-black-wide-screen-p-2143.html
Sound :
Your soundcard is great, but I think headphones are MUCH better then speakers, even surround-sound.
I'd get a set of these :
Sennheiser is probably the best, although the Rzer and SteelSeries are very popular too.
Case :
Keep your P180, it rocks!
If you're itching, the only cases you can "upgrade" to would be one of these :