At the start of the summer vacation i bought myself a 360, and a few games for it.
After playing GTA4 and Halo 3 i noticed the game have very bad anti-aliasing or none at all.

I use a Samsung SyncMaster 730BF monitor hooked up to the HDMI output via a DVI-HDMI plug.

The monitor has a native resolution of 1280x1024, and i can set this resolution in the Xbox Dashboard menu as well.

I've tried playing in 640x480 and 1024x786 and it still looks jagged.

Also, i don't have a TV to compare picture quality with.

Is this just a flaw in the games, or is it a problem with my 360?

No console war please, i made my decision already.

This might be your problem. Was it a cheap one?

Not really. It's still one of the better pc monitors to use.

I ment the DVI-HDMI plug. That's why it was enboldened.

sell me chips

Just chips?

Just Chips.

AA is done on a game by game basis. Some have 4x, some 2x, some have none. I know a lot of people were pretty disappointed with how jagged Halo 3 looked, I remember seeing a lot of very jagged screenshots when it came out. GTA4 I don't know about, but I'd imagine a game as big as that, with that much geometry, would struggle with a lot of AA applied.

Honestly dude, I think that's just the way the games look.

*slaps self for not noticing*

Well i don't really think so. HDMI is exactly the same as DVI, except DVI doesnt have a sound output. The plug doesn't convert anything except the connector itself.

Well, Halo 3 is just a jagged mess. Thats how the game was built. As for GTA 4, I noticed some jagged edges on some parts of the city while others are smooth as hell.