antennas, placement, kind, and surrounding area can make a difference. If you can stick you antenna outside or set it on the roof, may help. You could try in the window too.
I know some tuners are better than others. Although, I assume you're USB stick should be fine overall. Not that anyone one tuner is perfect for everyone, but if you're looking for small, you may want to look into HDHomerun. It's not as small as a USB stick. But rather than having something attached to your HTPC, it's just attached to your router. Basically, it is a network attached TV-tuner. It's very media center friendly.
I have and use one, the HDHR2. It works a lot better if your computer is wired to your router. The HDHR2 is a bit sensitive to radio interference. I didn't find it any worse then when I was using rabbits ears on my HDTV ten years ago. I've read the HDHR3 is not as sensitive comparatively to the HDHR2. I do all my DVR recordings with my office PC, and watch the recordings on my HTPC by sharing the libraries.
The DVR prices from satellite and cable are ridiculousness. I may be off on the pricing, but Comcast, in the past, charge $10 for the right to use it. The box was also an additonal $5 over a regular box. So, just by using the PC, you're going to save $180 year. Tack on the cable TV savings of approximately $600 ($50 TV service monthly bill), you'll probably recoup your money in about twelve to eighteen months, and then you'll actually be saving money. This is assuming you're buying everything new and not using old machines or parts.
As for Hulu, I recommend using their desktop program. It gives a really good experience. It's free too.