Which mobo/cpu to choose on a budget?

I've been upgrading my current pc over the last few months with a few new pieces with a mobo/cpu upgrade being the last piece to the puzzle, this will be my first build/swap and need some advise.

I use this pc mostly for gaming (wow) and for some work stuff involving large spreadsheets (two monitor setup). The gaming side is the reason for upgrading as all the other things the pc is used for run fine.

What I've upgraded is:

ATI HD 4850 video card
2 gb ram (max can currently run)
OCZ 500W Stealth Xtream PS
new case fans
PCI slot duel fan card cooler

The old stuff I planned to swap over:
200 gb sata hd
16x dvd r/rw drive
case (old but ok)
currently have a p4 3.06 on a asus mobo (ie the problem)

My goal is better game performance, while I don't need the best by any means or something to brag about, I don't want to look back and say "I upgraded for this?" Budget is a factor $250 would be the top (mobo, cpu, fan, glue, shipping, etc) while $150 would make me do backflips, just doesn't seem reasonable. FYI I don't ever plan to crossfire my ati card and I don't have a problem oc'ing a bit to stay on the safe side but his pc is running nearly 24x7.

The E8400 seems like the most common choice to date for my needs but I can't seem to squeeze it in my budget
http://www.newegg.com/Product/Prod [...] 6819115037

The E7300 may work
http://www.newegg.com/Product/Prod [...] 6819115132

With either of these it seems it's hard to get a mobo under $120 so I'm on the edge of my budget. I was originally looking at some intel x2 combos but have been steered away from those by a few friends.

Is there any reccomendations for a mobo/cpu combo that I'm really missing out on that would fit into my performance/budget problem? BTW I've read the $500 build but feel I can do a bit better than what they used there.

Lets see if I can get close to $150

MB: http://www.newegg.com/Product/Prod [...] 6813186147
$65 Foxconn A78AX-S
CPU: http://www.newegg.com/Product/Prod [...] 6819103254
$100 AMD 8450 Tri-Core

Total: $165 + S&H (not counting MIR, or specials/combos)

I'd personnaly add 4GB of ram later

http://www.newegg.com/Product/Prod [...] 6820231166
$80 (DDR2 1066 G.Skill)

A great budget motherboard for overclocking is the Gigabyte GA-EP45-DS3L Add an e5200 and a descent heatsink and you should be able to overclock to 3.6ghz at least and have very good performance for cheap.