I am back.
Info from Service Tags, what is applicable in selection only, no SS#, just kidding, no personal info located there, so you know.
Configuration as shipped.
Optiplex 755.
PROCESSOR, E8400, 3.0, 6MB, WFD, 65W, C0
DUAL IN-LINE MEMORY MODULE, 1G, 667M, 128X64, 8, 240, 1RX8 -
2 each,
DUAL IN-LINE MEMORY MODULE, 512, 667M, 64X64, 8, 240, 1RX8 -
2 each, so overall, 3 GB RAM
WXPPSP2 - Win XP PRO SP2
J229H
1
KIT, Software, VB32SP1A, Digital Video Disk Drive, Multiple, 5 -
DELL WINDOWS VISTA BUSINESS 32-BIT SP1 (J229H) upgrade
HARD DRIVE, 160GB, S2, 7.2K, WESTERN DIGITAL, XL320,
it is listed twice, so there is possibility of 2 hard drives
ASSEMBLY, DIGITAL VIDEO DISK DRIVE, 16X, Serial ATA, HALF HEIGHT, PLDS -
which is 16X SATA DVD-ROM Drive DH-16D3S, which is Lite-On:
Read Speed
48x (CD) / 16x (DVD)
Supported Media Formats
CD Extra, CD+G (Karaoke CD), CD-DA (audio), CD-I, CD-ROM, CD-ROM XA, Photo CD, Video CD
Supported Media Types
CD-R, DVD-ROM, DVD-RW, CD-ROM, CD-RW, DVD+R, DVD+R DL, DVD+RW, DVD-R, DVD-R DL, DVD-RAM
TC935
1
KIT, COMPACT DISKETTE, DRIVER, RESOURCE COMPACT DISK (CD), OPTIPLEX, V2
TC935 is actually motherboard model
Optiplex 760
KIT, SOFTWARE, OVERPACK, WXPPSP3, COMPACT DISKETTE W/DOCUMENTATION, ENGLAND/ENGLISH -
WinXP PRO SP3
U344C
1
Label, Certificate Of Authenticity, Operating System VB32/64, V#2008
U344C stands for DELL WINDOWS VISTA BUSINESS OEM ACT LICENSE (U344C), is it 32 bit or 64 bit, it is unclear, it seems that originally it was shipped with XP, but there was upgrade to Vista included.
J229H
1
KIT, Software, VB32SP1A, Digital Video Disk Drive, Multiple, 5 - i
t is clear now DELL WINDOWS VISTA BUSINESS 32-BIT SP1 (J229H)
PROCESSOR, E7300, 2.66, 3MB, WFD, 65W, M0
ASSEMBLY, DVD+/-RW, 16X, Serial ATA, HALF HEIGHT, TOSHIBA SAMSUNG STORAGE TECHNOLOGY -
16X, DVD+/-RW, looks like produced/rebadged by Dell
HARD DRIVE, 80G, S2, 7.2K, 8M, LEAD FREE, SGT-NH
DUAL IN-LINE MEMORY MODULE, 2G, 800M, 256X64, 8, 240, 2RX8 - 2 GB RAM
DUAL IN-LINE MEMORY MODULE, 1GB, 800, 128X64, 8, 240, 1RX8 - 1 GB RAM, so total is 3 GB
P583N
1
Assembly, Chassis, Matrix, Smith, Mini Tower, Pentium M Dothan, 2.0GHZ, 2 MEGB, 533FSB, Active Power Factor Correction, Pwa Integrated, Third Party Maintenance
That what we had been looking for, motherboard, let see,
U562N - Motherboard, Smith MT, Smith Bases P583N & P584N, TPM For Dell Optiplex 760
I think case is closed based on documentation provided by Dell, ugh
So, based on service tags provided, Optiplex 760 is the winner.
Now, just to be sure, open 760 and look for a small square label right next to PCIE slot close to CMOS battery
Label looks like this
Where 0F373D is motherboard model (for Optiplex 760 SFF)
Location easier to see here
Which is the picture of your motherboard.
Good luck checking.