A second welcome
, though it'd be nice to see your first post in the "Introduction Section"(followed by this thread in the "PC Peripherals" section).
800GBP should be about 64,000 INR or 1,35x USD.
Firstly, it seems you've done a fair bit of homework, so there aren't many changes to suggest, just a few important ones
:-
Motherboard:- Gigabyte GA-MA770T-UD3P (AM3 w/ DDR3)
CPU:- AMD Phenom II X4 955 Black Edition (AM3)
RAM:- G.SKILL 4GB (2 x 2GB) 240-Pin DDR3 SDRAM DDR3 1333 (PC3 10666)
GPU:- XFX 4890
HDD:- 500GB Western Digital Caviar Black
Case:- Antec Sonata w/ 500W EarthWatts PSU
OD/Monitor as per your preference.
The main changes i've suggested is the use of the AM3 socket and DDR3(seconding
G33kgod's suggestion), i believe there's not much point going with AMD for the better platform yet sticking to an older socket/older spec. memory.
*Firstly, The motherboard suggested, while cheap, is extremely good VFM, one hell of an OCer and super stable, easily one of the best boards out there for the price.
*Secondly, since the x4 940 doesn't go with DDR3, consider the current AMD top-chip, the x4 955 BE.
*Next, some fast 1333Mhz DDR3 Memory to go with the rest of the setup.
*GPU choice remains unchanged, as does the brand, not only do the XFX 4890 seem to OC better than the rest, the dual-lifetime warranty makes it a no-brainer.
*As for the HDD, while the Seagate 7200.12 are a bit faster, nothing beats WD reliability and that 5 year warranty(Seagate no longer covers their drives for 5 years[or do they? :-
http://www.techenclave.com/storage-solutions/seagate-warranty-status-3yrs-or-5yrs-125722-3.html), so WD Caviar Black it is.
*Coming to the case/chassis, the one you've listed is easily the best combo in the market. The Sonata is a beautiful case with a piano black finish bundled with excellent fans(variable RPM antec tricool's) and very, very quiet. Meanwhile, the PSU that comes with it is an 80plus certified highly efficient EarthWatts 500W. A Seasonic OEM that is comparable to the VX450.
Now to answer your queries:-
1)Future AM3 processors can be slapped in on this board, so as long as you're not going to run a mult-GPU setup(and you don't need to), you won't be missing much from the more expensive models.
2)Yes, this PSU will power your system.
3)This question is subjective, but for now, im going to say no, it wont be loud enough for you to worry about it atleast at idle, and you should be able to stick to the stock cooler till you start thinking about overclocking(and you should, since all these components are very capable, and you can extract a lot from them. If you have doubts, read guides and ask around, people will be more than willing to help
)
You can expect the antec to contain most of the noise generated by your system.
When i add it up, the setup comes upto about 430GBP excluding the price of the optical drive and the monitor.
Few cliff notes:-
*Try and accomodate a 24 inch monitor(not necessary though), as prices are low and your system will be capable...
*If you aren't sure weather you need this much power, consider going for the X2 550 BE dual core Phenom II. For most usuage, you may find this to be more than enough, and it's cheap so you can just swap it for a fast quad core in a few months if need be(not to mention said quad will be a lot cheaper when you eventually do buy it). Also, the motherboard suggested above also gives you a shot at unlocking the disabled cores, though not guarnteed, getting a quad core for ~60 odd GBP is quite the temptation. It's a very capable processor even w/o the unlocking, and if you find it to suffice your needs, it'll save you a good many quid.
*Do consider Intel core i7 options at this budget, you may be able to shoe-horn a system(with a moderate budget increase maybe?) with a few more bells and whistles(albeit, sacrificing the Graphics processing a bit, possibly), a fancier platform(tri channel memory etc.) and maybe even a sizeable performance advantage. Although, entirely optional, as the build suggested above is more than capable already.
*Make sure you get the optional front mounted antec tricool along with the Sonata III
If you have any questions/ need some alternatives/ have anything else to say, please post.
All prices were taken from newegg.com.
PS: Im a bit sleepy, may have messed up some conversions, please let me know, if any.
PPS: Post has been edited multiple times, just incase you caught me while updating it...
).