First, the distinction between "Type 1" and "Type 2" hypervisors is rather blurred these days. It's certainly a bit different than the original 1973 definition. After all, many of the hypervisors commonly referred to as "Type 1" are not actually bare metal hypervisors, but rely on a host OS to some extent.
These days many people say "Type 1" when they mean "server" and "Type 2" when they mean "workstation." These are not the original definitions, so paying attention to this artificial distinction will be quite confusing.
It's more useful to determine whether the hypervisor can accomplish what you want to do.
With that out of the way:
All of the popular hypervisors provide reasonable near-native performance once guest tools/paravirtualized drivers are installed. The main exception to this is 3D graphics, which will typically run poorly compared to native performance even with drivers.
While it's possible (with a processor that supports VT-d) to reserve a host video card for the exclusive use of a virtual machine, this is not well supported in many hypervisors as they concentrated their development of this feature on giving VMs raw access to network cards.
If you're a gamer, you should consider running a desktop virtualization solution such as VMware Workstation or VirtualBox so that you can game on the host OS and have the highest possible performance from your games.
If you want to share data between your guest OSes, you can either create a VM specifically for this purpose, or use features of the various virtualization solutions to provide access to folders on the host's hard drive (e.g. VirtualBox and VMware Workstation provide "shared folders" which maps a directory on the host hard drive to a virtual hard drive or virtual network share in the guest).
I've edited your question to reflect what you are actually asking for; a type 1 hypervisor runs directly on the hardware while a type 2 (such as VirtualBox) runs inside a conventional OS like Windows. – Bob – 2012-06-17T07:14:55.447
Windows 7 should work fine. However, you will want to look at whether your processor supports IOMMU/VT-D, which should let you access some devices directly. Would make a huge difference for gaming related things, since your VM would be able to directly use your video card i think – Journeyman Geek – 2012-06-17T07:19:09.777
My CPU is a core i5 2500k, which supports (in the BIOS) something called only "hardware virtualisation" – Rory – 2012-06-17T08:20:40.173
AFAIK their is no Type 1 Desktop Hypervisors. Other then a product from Citrix specifically aimed at a limited selection of laptops and only useful in conjunction with their enterprise VDI solution. Since what I think you want doesn't exist yet everything you are asking is basically moot. The common Type I hypervisors (ie ESXi, XEN, KVM, HyperV) are pointless on a Desktop system. – Zoredache – 2012-06-17T10:10:48.070
http://superuser.com/questions/234837/i-want-to-virtualize-my-workstation-tier-1-looking-for-bare-metal-hypervisor http://serverfault.com/questions/386762/is-it-appropriate-to-run-hyper-v-server-on-each-desktop-pc http://serverfault.com/questions/368291/why-use-a-type-2-hypervisor – Zoredache – 2012-06-17T10:18:10.620