Please have a look at this system

I have a pathetically low spec system atm. I manage to run games thorugh it well, but only after quite a bit of tinkering around, and I don't now how much longer my mobo wil be able to cope (it's v.old, has no AGP slot for reference as to its age)

Here are the parts I am thinking of getting currently (I am on a shoestring budget, just so you know-I'm not particularly tech savvy either, so forgive if I make some major flaw or error)

AMD Sempron 2800+ (sda2800dut3d) Processor 256KB Cache FSB333 - OEM
£61.42 ($114.40)

Abit NF7 V2.0 nForce2 Socket A 8xAGP LAN USB2 6 ch Sound DDR400 Memory Retail Box
£41.99 ($78.19)

Sapphire Atlantis Radeon 9800 PRO 128 MB DDR 8x AGP DVi & TV-Out - Retail Box
£130.17 ($242.39)

Ebuyer 500w Power Supply Black With Dual Fans
£14.09 ($26.24)

Speeze EEA30B4 Lightowl AMD CPU Cooler Xp3200+ and Sempron 2800+ With Green Led Lights
£7.04 ($13.10)

120mm Internal Case Fan In Black
£0.82 ($1.50)

Total Price: £255.53 ($475.82)

I think (hope) this should all fit together quite nicely and I would end up with a nice little system (for the price).
I have an 80Gb hdd, a stick of 512ddr ram cd-rw(48x) dvd(16x) combo drive, 120ml case fan, a pci gfx card and a 10mbps NIC from my old setup. (plus the caseitself of course)

My questions:
1)Is it worth the money?
2)Can I get more value for that money (a better system for around the same price)?
3)How long will that system be able to run top of the line games? EG. Will I need an upgrade to play HL3/UT2006 in a few years time?
4)If I will need an update to utilise the latest software in a few years time, then how much will I have to spend? EG a new gfx card, or just a new cooling system? (something expensive or something cheap)
6)Could I get an equivalent system for LESS than this current price (if yes, links please!!!)

I will answer any questions you need for you to give me advice (I would VERY much appreciate any advice you can give me)

Thanks in advance, Waffler

For a slim budget, it looks good.

I would however recommend THIS power supply instead

As a system builder we are now selling a lot of these and they hold up really well in that they have two thermally controlled cooling fans...

Just as long as you realize the fastest cpu you can put in that board is a 3200 + (Athlon XP). They are still out there. I think newegg has them for $182.