There are usually one or two "interesting" (ie, semi decent) parts in the bundles, together with a bunch of crap. Let me show you what I'm talking about.
http://www.tigerdirect.com/applications/SearchTools/item-details.asp?EdpNo=3537281&Sku=S458-1296%20A
Heres a good example. Phenom, 2GBs, 400W PSU, $415. Sounds good? The first knock against it is the ECS motherboard. Its not exactly the best. Features wise its not bad, but don't expect the overclocking abilities of a Gigabyte or Asus. Tiger lists it at $70, but its currently out of stock at newegg for ~$60 after rebate. It might be available somewhere else for closer to the $60 point.
The "interesting" part of this bundle is the Phenom. I'm sure you know about the chip. Tiger and newegg sell it for the same price, its the good part of this bundle.
http://www.newegg.com/Product/Product.aspx?Item=N82E16820227139 I'm not sure if this is the "platinum" OCZ series ram, but it is OCZ ram with 4-4-4-15 timings for $41 after rebate. If you wanted to spend $70 on your ram, you could get this.
http://www.newegg.com/Product/Product.aspx?Item=N82E16820227199
Thats 4GBs of OCZ ram (5-5-5-18) for ~$80. An extra $10 could get you double the amount of ram.
Now comes the crap they are trying to get rid of. An ultra V series 400W PSU. This is probably mega crap, and shouldn't be ran in any system. But Ultra has to get rid of them somehow, so why not throw them into a bundle...
The best part of that bundle is the CPU. The motherboard is alright for a budget motherboard, but its not the nicest motherboard out there. The ram is ok, but better deals are out there. The case is probably fine, but you better chuck that PSU if you care about that 8800GT that you have planned. (most current high end cards say you should have a 450W with 30A on the 12V rails, that one is probably short.)
As I also pointed out, the other problem is price. You can find parts cheaper, or spend the roughly the same amount and get better/more. I used to like looking at the tiger bundles until this dawned on me.