Both Battlefield 3 and Crysis 2 state that they require a dual core processor at the minimum. So no you wouldnt be able to run the latest games on a Intel® Pentium® 4 processor. Really you need to be looking at an Intel Core™ 2 Duo or later processor, heck I would be looking at something like the Intel Core i3-2100 on the low end.
It's best to buy a new PC if you want to play current games. The vast majority of recent games require a dual core CPU. A few uses 3 or 4 cores.
As mentioned above, the Core i3-2100 is a good entry level CPU for games. If you are really strapped for money then you can build a new PC around a CPU which costs less than $100. Such as the following (based on Newegg.com prices)
If you have a pentium 4 in your computer chances are let alone that your processor won't fun the game, non of the other hardware will run the game either, there are things such as dx10 compatability, shader versions. chances are if you are running a motherboard with like an AGP video card or something. so no , just no