I think with a BIOS update you could run a 1.4 T-bird. I have the same board running a 1 gig. Can't remember which BIOS it has right off the bat. It also has a Geforce 2 Ultra in it. It's my wife's Solitaire machine now. It has basically the same components as yours except the 1 gig chip.
The A7V is a 100 FSB MOBO. 1.4 Tbird is a 133 FSB chip. So you wouldn't get the 1.4 out of it I don't believe. My 1 gig is a 100 FSP chip & the 1.2 & 1.4 came out @ 133 I believe. The A7V-KT133 MOBO supported these chips.
I rebuilt last Nov. myself to upgrade from where your at now. Sorry if I sounded rude.