Code:

dmidecode | less

out put

Gives you alot of good info about your hardware. As far as OS, I suppose it depends on what your looking for. Like version number, you could run 

SMBIOS 2.3 present.

55 structures occupying 2343 bytes.

Table at 0x000F8795.

Handle 0x0000, DMI type 0, 19 bytes.

BIOS Information

        Vendor: IBM

        Version: -[KPE137CUS-1.12]-

        Release Date: 02/16/2006

        Address: 0xF0E00

        Runtime Size: 61952 bytes

        ROM Size: 4096 kB

        Characteristics:

                PCI is supported

                BIOS is upgradeable

                BIOS shadowing is allowed

                Boot from CD is supported

                Selectable boot is supported

                Japanese floppy for NEC 9800 1.2 MB is supported (int 13h)

                Japanese floppy for Toshiba 1.2 MB is supported (int 13h)

                5.25"/360 KB floppy services are supported (int 13h)

                5.25"/1.2 MB floppy services are supported (int 13h)

                3.5"/720 KB floppy services are supported (int 13h)

                3.5"/2.88 MB floppy services are supported (int 13h)

                Print screen service is supported (int 5h)

                8042 keyboard services are supported (int 9h)

                Serial services are supported (int 14h)

                Printer services are supported (int 17h)

                CGA/mono video services are supported (int 10h)

                ACPI is supported

                USB legacy is supported

                I2O boot is supported

                LS-120 boot is supported

Handle 0x0001, DMI type 1, 25 bytes.

System Information

        Manufacturer: IBM

        Product Name: eserver xSeries 346 -[8840CF1]-

        Version: Not Specified

        Serial Number: 99CDKWF

        UUID: F6434345-28B4-4A12-BFF0-E8A86CC3E7F6

        Wake-up Type: AC Power Restored

Handle 0x0002, DMI type 2, 8 bytes.