If you have got hardware on your system, but are not sure of the manufacturer of that device and hence where to download drivers for it, then this might help. Note that it is not exhaustive, and that there may be omissions and possible errors.
PCI Vendor and Device Lists
To use it, simply find the relevant device IDs in the Device Manager. I shall use my graphics card as an example.
To get this information, open the Device Manager. Click to expand the category you are interested in and then double-click the relevant sub-category (alternatively, click on the sub-category and then click on the Properties icon). In the Properties page that appears, click on the Details tab. In the Properties dropdown, select Hardware Ids. The information you require can usually be found in the first entry.
The information that we want is already highlighted, so let's have a look at it in more detail. I've copied it here, to make it clearer.
PCI\VEN_10DE&DEV_0611&SUBSYS_00000000&REV_A2
We are only interested in the data highlighted in RED (the vendor) and BLUE (the device ID).
Now that we have got this information, we need to input it on the website (link given above).
Clicking on Search yields the following.
Vendor search: (Useful for identifying the manufacturer's website.)
Device search: (Identifies the device itself. Note that you need to match both IDs here.)