How much can I sell this system?

I have this system I was thinking of selling:

Core 2 Duo E6400 @ 2.13 GHz
2 GB RAM PC-5300
ATi HD 4850 512 MB
400W PSU
ASUS P5B mobo
250 GB HDD Western Digital
DVD-ROM
DVD-RW
Floppy with 7 in 1 card reader

First I was thinking of overclocking or upgrading, but then I rejected the first option since I know nothing of these things (I made some posts on the other forum categories) and was thinking about the second. But I realized that I wanted a faster memory, a PCI-Express 2.0 mobo and definitely a new processor and a new PSU to hold all that in place. Only thing worth keeping is my graphics card which I bought for 85 euros (that's around 110 dollars or 50 pounds - my previous card got "burned" due to Greek heat waves and it was still in warranty so I got the 4850 for half its original price), which means I can actually make money off of it.

So, how much do you think I can sell it? I could just leave its Windows XP in there (after formatting and reinstalling of course), but I can leave that up to the buyer. So, any suggestions? Thanks in advance.

PS: I am only talking about the case; no monitors, speakers, or any peripherals whatsoever in the deal.
PS2: If you have any other suggestions about what I can do to future proof my system (2 years ahead), without spending more than 600 euros, please share.

I cacn but a system just like that w/o the GPU but a faster process from Dell for $430 w/ 19" monitor and 1yr on-site warranty.

That would be abour $250 for they system after reselling the monitor.
Considering yours is used, I would say it's worth maybe $200 if you include the XP CD w/Serial#.

The GPU is worth almost as much as the rest of the system, so I would sell that seperate.

Now, I would put a cheap GPU in it and try to sell it for about $300 on CraigsList and mark down as necessary. Any offer in the $200-$250 would be a fair offer to accept.