Regarding the Cheats & Hints.
It is possible to freeze your current amount of scrap metal through Protector Casdin (confirmed on 360). This method can be done directly after leaving Vault 101. Moderate sneak skill is required, around 30-40, which can of course be supplemented by Stealth Boys.
* 1: First, an even number of scrap metal is needed. The RobCo Facility and the Meresti Station are two places with a lot of scrap metal.
* 2: (Skip if friendly with Outcasts) Collect various items for Casdin, enough to achieve allied status with the Outcasts. The best place for this is the UFO crash site to the north, not only since the loot yield far more points than required to become friendly with the Outcasts, but also because one can simply stop by Meresti Station on the way and loot the scrap metal there.
* 3: (Skip if friendly with Outcasts) Speak with Defender Morgan to start The Outcast Collection Agent quest.
* 4: (Skip if friendly with Outcasts) Give Casdin enough items to become friendly with the Outcasts, around 50 points worth of items.
* 5: Give Casdin all scrap metal in your inventory. This batch is the X Value. Note! This value MUST be an even number (10, 12, 14 etc).
* 6: Steal back the X Value scrap metal you gave Casdin.
* 7: Give back all scrap metal EXCEPT 2 for the best possible profit. This batch is the Y Value.
* 8: Steal back the Y Value scrap metal from Casdin.
* 9: Now, attempt to steal one of Casdins basic items, such as his Laser Rifle (or if you've given them to him, the Alien Power Cells). You should get caught (if not, try again). Casdin will then proceed to take back his scrap metal, but will steal back both the X Value and the Y Value. For example, if you gave him an 16 scrap metal, stole them back and then gave him 14 scrap metal, it will say that he removes 14 scrap metal and then 16 scrap metal.
This will glitch your scrap metal value so that you have a Z Value which is negative. It will appear as if you have no scrap metal at all in the inventory, but when you speak with Casdin, Winthrop or Walter you will still have the option of giving them scrap metal.
Following the example above, if you first gave him 16 scrap metal, stole them back and then gave him 14, you will have 14 invisible scrap metal in your inventory that can be given away to Walter, Casdin and Winthrop. Most importantly, this amount of invisible scrap metal is permanent, meaning it can be given away infinite times, as long as you do not pick up any additional scrap metal (which will reset the negative value back to normal).
Used early in the game with Walter, this gamebreaking glitch can launch a level 2 or 3 character to level 20 in less than 20 minutes, netting around 45,000-60,000 caps in the process.
Taken from fallout.wikia.com/wiki/Scrap_Metal#Glitches_and_bugs I take no credit for finding this glitch. I will be testing it out on a new character sometime soon. This seems like it will be great for trying out a new build for your character and starting fresh on all the quests.[Edited by Zackman, 5/5/2009 8:59:58 PM]