Need Advice on an aging system!!...HELP!!

For the last 4 years I have been running a self built system with an Athlon 64 3200 CPU, a MSI K8N Neo Platinium MOBO (Socket 754), 1.5 GBs of Corsair PC 3200 RAM, an XFX GeForce 6800GT AGP vid card, WD Caviar 80 GB SATA HD, Augigy 2 sound card, Aerocool 450 Watt PSU and windows XP SP2........its ran just beautifully all these years........stock......and until last week when I lost my decent paying job, I was gunna build a whole new system, until my a$$*#$% of a boss ruined all that and all my other plans when he gave MY job to his out of work friend!!.....I had all my parts picked out....now I'm unemployed...possibly for some time...So...needless to say..I'm on a fixed budget.....have some money saved...but....need to conserve most of it....I wanna keep this system alive and kicking for the next 6 mos?...to a year?....but not spend more than $300 to $400 to do it......I wanna play some games that have come out in he past few months that don't run all that well on my current set-up....namely...CRYSIS (downloaded the demo...had to run it on low settings, it was playable but looked like crap!), COD4 (same deal....altho the framerate was much better), BIOSHOCK (Demo ran surprisingly well...on lower settings...decent framerate....but not good enough where I wanted to buy it) and when it's released STALKER:Clear Sky (STALKER:SOC runs Great on my system!...most settings on medium to high)...altho the new STALKER game has a beefed up engine and may struggle a bit. I was thinking of upgrading my vid card to a faster AGP card.....like a Radeon 2400-2600 or higher....or a GeForce 7300-7600....I could do that for $100 .....then I was thinking....of upgrading my CPU as well to an Athlon 64 3700.....400MHz faster....get a little boost there as well....I can get 1 of those for less than $200....throw in a bigger HD and maybe a bigger PSU for $50-$100.....and hopefully crysis,COD4 etc.....will be playable and look a little better?...good enough for me until I'm working again and can build a new system.....$300-400 is all I can spend for now...So my question is...would this make a difference?....would i see an improvement to make spending the dough worthwhile?.....I'd be happy with a 30% or so improvement.....or am I just throwing that money away?........I really dont want to upgrade the type of MOBO I have (Socket 754)...because then I have to upgrade the RAM.....too....AND the vid card...AND the CPU...and thats too much..I'd appreciate any advice.....sorry to be so long winded...but wanted to include as many details as I could...Tahnks!

I tried reading but its like a torture to the eyes man.

GL whoever helps this guy.

This video card- http://www.newegg.com/Product/Product.aspx?Item=N82E16814161225

This hdd- http://www.newegg.com/Product/Product.aspx?Item=N82E16822148294

And if you really want a new psu get a corsair 450 watt. That leaves u with enough to get a decent heatsink to just overclock your cpu.

I don't think you can get too much out of that mobo. You would need to redo a lot of it to get a decent system. However you want to make it last 6 months you would just need a better gfx card since htat is the only thing that is worth an upgrade with your system.

This card is the best AGP card.

http://www.newegg.com/Product/Product.aspx?Item=N82E16814102730