I have a pretty large mod list, but my game is pretty darn stable...runs at worst 20 mins, at average 2 hours, at best...all night long. crashes are the ctd variety, with the occaisional sound lockup. If you have a sound CARD, you might not have even the few crashes I have, as I use onboard sound.
Click the 'spoiler' button below and it will list my load order. NOTE that bashed patch is always LAST. Move it around with ALT+arrow up or down to get it into that spot AFTER you hit the BOSS button in Wrye Flash.
To get FLASH working, you have to find the version of PYTHON that was recommended for wrye flash/bash on the FO3NEXUS (2.5.7 or something like that?).
Install the following:
BOSS
WRYE FLASH
WRYE PYTHON
Copy bashed Patch, 0.esp into your data directory..it should be in mopy/extras I think.
If you have the right Python installed (NOTE: Flash will *not* work with newer versions of python..ONLY with the one recommended for the FO3 version of flash/bash!), then a box will pop up when you run wyre flash launcher.pyw (something like that..I made mine a shortcut on desktop and renamed it). and say 'loading windows'. After a few seconds, a window will open up listing your mods.
CLICK on the COLUMN HEADER named 'LOAD ORDER' until you see numbers listed in that column starting with 00 (falloutnv.esm) and ending with bashedpatch (again...move it to the end).
Now click the BOSS button. your browser will open up and you can review the load order and any notes on errors.
Again, shift the bashed patch to the end of the load order!
NOW, higlight (single LEFT click on bashed patch, then use shift+arrow up) the ENTIRE list, including the bashed patch, all the mods, and the .esm files.
RIGHT click the highlighted list and select MARK MERGEABLE.
Now single click on the bashed patch again to unhighlight the list. then RIGHT click bashed patch. select REBUILD PATCH.
Options you need to tick are:
Alias mod names
Merge Patches (on the right side panel click SELECT ALL button to ensure all mergeable items are set to, in fact, be merged!!!!!!)
Contents checker
FormID Lists (IMPORTANT!)
Leveled Lists (IMPORTANT!) Make sure on these last two that everything on the right side panel has a checkmark!
You can optionally use the 'tweaks' options...I personally let it sort my inventory, and thats about it.
click BUILD PATCH.
a minute or so later...et voila...patched and ready to rock!
BELOW is my load order...your desires may vary (note: this is my 4th playthrough so some mods I have kinda would blow the immersion on a first run)
Spoiler FalloutNV.esm
ClassicPack.esm
MercenaryPack.esm
IWS-Core.esm
More Perks.esm
Weapon Mod Expansion.esm
Lings.esm
TravelingMerchantFix.esp
DarNifiedUINV.esp
SaveKey.esp
VendorGameTimeRestock.esp
UHNV.esp
UHNV-Performance-Patch.esp
markers.esp
CONELRAD 640-1240.esp
SecretStash80.esp
WPR.esp
xatmosSkillPerks.esp
Better Tag Skills.esp
DK_BulletTime_NV.esp
PortableCampsite.esp
WMR_WME_S.esp
QS_Blackwolf_NV_Backpackmod.esp
bzArmour.esp
Eyepatch.esp
Realistic Power Armor.esp
Realistic_Repair_NV.esp
Light Step ED-E.esp
aaaJNFSniperZooming.esp
noautoaim.esp
Nevada Skies.esp
Armor block 100.esp
ColdTurkey.esp
UsableCigarettes neunen Ver for New Vegas.esp
Bashed Patch, 0.esp
Level Cap + Perk Every Level.esp
Total active plugins: 36
Total plugins: 40
Note: anything in my load order that does NOT have a checkmark is a file that FLASH 'merged'. These appear after the patch build as having a + sign instead of a check mark next to them.
Enjoy and sorry so wordy a post...but I wanna make sure you dont have any headaches doing this

Oh yeah...turn UAC (user access control) *OFF* if your system (vista or win 7) has it. Its pointless and causes issues with games like this one. Might reinstall and repatch after turning UAC off, your choice.