Hi to all members of this beautiful community! I'm a new member from Greece, but also a long time lurker 😉 And -as usual- i decided on a membership just when i wanted help...
I know there are various posts about possible ideas/solutions, i've read many of them, but in the end every case is different.
I've had over the years various pcs from which i saved some parts (unfortunately not from my oldest ones) and also got some more from here and there.
So, without further ado, my problem...

I want to build 2 PCs, one for Windows 98SE/Dos and the other for Windows XP 32bit capable for playing most of the games available at their respective eras.
But i'm struggling to select the "right" parts that are available to me (of which i don't know how may are in working order).

CPU's i' ve got:

Celeron 700 (Socket 370)
Celeron 1100 (Socket 370)
Intel Pentium 3 1000/256/133 (i'll have it in a month or so)
Intel Pentium 3 SL5QL 1266/512/133 (i'll have it in a month or so)
Pentium 4 1.7 Willamette (s478)
AMD Sempron 2600 + (socket A aka 462)
Pentium 4 2.8 Ghz Northwood (s478)
Pentium 4 640 3.2 Prescott (LGA775)
Pentium 4 641 3.2 Cedar Mill (LGA775)
Pentium 650 3.4Ghz Prescott (LGA775)
E8500 3.16Ghz (LGA775)
Q6700 2.66Ghz (LGA775)

MOBOs:

-for 370-
Gigabyte GA-6VTXE rev 1.0 (VIA Apollo Pro 133T )
*Elitegroup P6BAP-A+ v2.2 (VIA Apollo 133)
Gigabyte GA-GVXC7-4X-P rev 5.0 (VIA 694X) coming in a month with the P3s

-for s478-
*GIGABYTE GA-8PE667 Ultra Rev 1.0 (Intel 845PE)
GIGABYTE 8S648FX-RZ rev: 1.0 (SiS648FX)

-for socket A / 462 -
*ASUS A7N8X-X (NVIDIA nForce2 400)

-for LGA 775-
*GIGABYTE GA-965P-S3 (Intel P965 Express)
*GIGABYTE GA-965P-DS4 (Intel P965 Express)
*MSI P35 Neo2-FR (Intel P35)
MSI MS-7143 Ver.2B (Intel P915 PL)
ASUS P5G41T-M LX2/GB/LPT (Intel G41)
ELITEGROUP G31T-M7 rev:7.0 (Intel G31)
INTEL DG31PR (Intel G31)
GIGABYTE GA-EP35-DS3 rev:2.1 (Intel P35 Express)
GIGABYTE GA-VM900M rev:2.0 (VIA P4M900)
GIGABYTE GA-G31M-ES2L rev:2.4 (Intel G31)
* bought new from me/my family, all others unknown condition

-Graphic cards-

-AGP-
*S3 Savage 4 16Mb AGP (AGP 3.3v)
**PROLINK PIXELVIEW MVGA-NVG28A DVI 128MB W/TV (Nvidia Geforce 4 Ti4200)
*ALBATRON FX5900XTV Nvidia FX5900 128 MB AGP 4X/8X
*ASUS V9999/TD/N/128M/A GeForce 6800 128 MB AGP 4X/8X
**XELO TNT2 M64 32MB 32 mb AGP 4x
***PixelView NVIDIA GeForce MX4000 64MB DDR 64mb AGP
***Leadtek Winfast LRI 2816 Geforce 2 MX400 32 MB AGP 4x
***Powercolor Radeon 9250 256MB AGP 4x/8x

* bought new from me/my family - working
** need fan replacement, unknown condition
*** unknown condition

-PCI-E-
*GAINWORD GeForce 7900 GS 256 MB PCI-E 1.0 x16
**ELITEGROUP N9600GT-512MX EDM 9600 GT 512 MB PCI-E 2.0 x16
*XFX Alpha Dog Edition 8800 GT 512 MB PCI-E 2.0 x16
***MSI NX8800 Geforce 8800 GTS 512MB
*GIGABYTE GV-R577UD-1GD HD 5770 1 GB PCI-E 2.1

* bought new from me/my family - working
** possibly damaged
*** unknown condition

-AUDIO CARDS-
*SB Audigy SE SB0570 - CA0106-WATLF PCI
*SB Audigy 2 SB0240 - CA0102-IAT PCI
**SB Live 5.,1 SB0060 PCI
**SB Live CT4760 PCI (coming in a month with the P3s)

* bought new from me/my family - working
** unknown condition

For the Dos/Win98SE PC, i'm thinking of either using one of the following setups:
a) Gigabyte GA-6VTXE rev 1.0 + Celeron 1100 (later to be changed with the PIII 1.26Ghz) + Geforce 4 Ti4200 (if it's still working, my memory fails me) + SB Live! SB 0060 or CT4760 (i've failed to find an ISA soundcard in Greece so far at a "normal" price)
b) ASUS A7N8X-X + AMD Sempron 2600 + (so far availability of Athlon XPs has been nonexistent) + FX5900XTV or GF6800 + SB Live! (SB 0060 or CT4760)
c) something based on a P4 ?

For the WinXp 32 bit, i'm currently set on this one:
GIGABYTE GA-EP35-DS3 rev:2.1 (all solid caps) + E8500 3.16Ghz (fastest dual core CPU i've got) + HD 5770 (best pci-e i have, tempted to test the 8800s) + Audigy 2 ( SB0240 - CA0102-IAT) (i thought about getting an X-Fi, but i can' t see the benefit of that move)

Any thoughts are most welcome!