EDIT: *smacks self for stupid mistake, there is no new patch out for OFB*
Err.. I guess I can still make this something useful, it will need to be moved though methinks...
To check what version the file is (because Maxis has a stupid habbit of making them the same name), you can use a program like QuickSFV (
http://www.quicksfv.org/) to compare the md5.
Patch 1 (version 1.0.0.971)
-----------
Original file name: thesims2_update_cd.exe
MD5: 265ac36a6c81b09109b46c59bc53f30a
Original file name: thesims2_update_dvd.exe
MD5: e77ce86d908af50203842e9465f80309
Patch 2 (version 1.0.0.994)
-----------
Original file name: thesims2_update.exe
MD5: a9ce29ea541d8c88ce69b0f5cf1f958a
Patch 3 (version 1.0.0.999)
-----------
Original file name: TS2UPD.exe (University)
MD5: ed95ffe9f49d812fca86d371c0368aa9
Original file names: thesims2_update.exe & TS2UPD.exe (Nightlife, Holiday Party Pack, OFB)
MD5: 8529a7afb287eaa77fc069857cb49cfa
The patch included with University is the exact same as the one Maxis released on their website that fixed a problem with the Asian version of the game; it just has a different exe loader.
Patch 4 (version 1.0.0.1022)
-----------
Original file name: thesims2_update.exe
MD5: 4210359a62b1b494013b78a0b3f1ca64
University Patch (version 1.1.0.284)
-----------
Original file name: sims2ep1_patch.exe
MD5: fb20084ba58e0f437b1d7c7b3e98c622
Nightlife Patch 1 (version 1.2.0.337)
-----------
Original file name: sims2ep2_patch.exe
MD5: b8361e9d3fe9ef522428e77f8b369258
Nightlife Patch 2 (version 1.2.0.355)
-----------
Original file name: sims2ep2_patch.exe
MD5: 784613def8baf14480b14af846c66226
OFB Patch (version 1.3.0.280)
-----------
Original file name: sims2ep3_patch.exe
MD5: 9496f4820630f97ceca29e6dd5316b18
It may only be useful for people who archive junk, like what I'm doing, but it may have practical use if you can't remember what patch you have next time you reinstall.