Upgrad Advice - Please help choose MB/CPU config

Ok, I've narrowed my choices. I'm looking to very cheaply upgrade my
Soltek Athlon XP 1700+ computer. My graphics card will probably be an
FX5200 128 MB (or a GeForce3 128 MB), at least for the time being. I
just don't have much cash, but I need to upgrade this computer for MS
Flightsimulator. After searching ebay for a couple of weeks and
comparing to Pricewatch and the TomsHardware.com Athlon Benchmark, it
appears my best buys will be a MB/CPU combo from Compu-Terra. My
pricepoint is about $150 for the package, and these are the best
choices I could find for what I was looking for:

- Abit NF7-S2 with Athlon XP 2600+ 333 FSB - $139.74
- Abit NF7-S2 w/Athlon XP 2800+ 333 FSB - $162.90
- ASUS A7N8X-X w/Athlon XP 2600+ 333 FSB - $151.88
- ASUS A7V400-MX w/Athlon XP 3000+ 333 FSB - $152.95
- ASUS A7N8X-E (Deluxe) with Athlon XP 2600+ 333 FSB - $160.72
- Gigabyte GA-K8NS 754 w/Athlon 64 2800+ - $162.98

All these choices come with a fan. My basic assumptions are, based on
reviews at TomsHardware and elsewhere, that I'm partial to nVidia
nForce mainboards, and at this pricepoint, Athlon XP is the way to go
- I should stay away from Sempron (true?).

The best buy seems to be the Gigabyte 754 Athlon 64. Am I correct in
this assumption? It's too bad it's not a GA-K8NS Pro, but at this
price, I'll live with it. I already have a linksys 802.11g card,
which is how our house is networked at the moment.

Other suggestions at a similar pricepoint are welcome. Ultimately,
w/mem this will be $100 more than I wanted to spend, so I really
don't want to go higher.

Also, anybody know where to get a good price on 1GB PC3200 400 MHz
sticks?

Thanks,

Thomas