When you do find yourself running low on health, Salt, or ammunition, there is a decent chance Elizabeth will call out to you that she has something for you. With the press of a button you will receive a health or Salt vial, or an entirely new weapon with a filled clip, ready to fire. This happens in almost real-time during battles, so enemies keep moving while the item is thrown and caught. However, it did appear the enemies could not damage you during the perhaps second-long event. Oh, and in case you were worried, she does not need your help in combat. The game is not one giant escort mission."
Any major computer upgrade generally requires a full software reinstall too. No so if you heed the advice in the guide to Upgrading a Motherboard without Reinstalling. PCSTATS Tips